# Copyright 2010 Google Inc. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#     * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#     * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# IMPORTANT:
# Please don't directly include this file if you are building via gyp_chromium,
# since gyp_chromium is automatically forcing its inclusion.
{
  'variables': {
    # Variables expected to be overriden on the GYP command line (-D) or by
    # ~/.gyp/include.gypi.

    # Putting a variables dict inside another variables dict looks kind of
    # weird. This is necessary to get these variables defined for the conditions
    # within this variables dict that operate on these variables.
    'variables': {
      'variables': {
        # Compute the architecture that we're building on.
        'conditions': [
          [ 'OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
            # This handles the Linux platforms we generally deal with. Anything
            # else gets passed through, which probably won't work very well; such
            # hosts should pass an explicit target_arch to gyp.
            'host_arch%':
              '<!(uname -m | sed -e "s/i.86/ia32/;s/x86_64/x64/;s/amd64/x64/;s/arm.*/arm/")',
          }, {  # OS!="linux"
            'host_arch%': 'ia32',
          }],
        ],
      },

      'host_arch%': '<(host_arch)',

      # Default architecture we're building for is the architecture we're
      # building on.
      'target_arch%': '<(host_arch)',

      # This variable tells WebCore.gyp and JavaScriptCore.gyp whether they are
      # are built under a chromium full build (1) or a webkit.org chromium
      # build (0).
      'inside_chromium_build%': 1,

      # Set to 1 compile with -fPIC cflag on linux. This is a must for shared
      # libraries on linux x86-64 and arm.
      'linux_fpic%': 0,

      # Python version.
      'python_ver%': '2.5',

      # Determine ARM compilation flags.
      'arm_version%': 7,

      # Set Neon compilation flags (only meaningful if arm_version==7).
      'arm_neon%': 1,

      # The system root for cross-compiles. Default: none.
      'sysroot%': '',

      # On Linux, we build with sse2 for Chromium builds.
      'disable_sse2%': 0,
    },

    'target_arch%': '<(target_arch)',
    'host_arch%': '<(host_arch)',
    'inside_chromium_build%': '<(inside_chromium_build)',
    'linux_fpic%': '<(linux_fpic)',
    'python_ver%': '<(python_ver)',
    'arm_version%': '<(arm_version)',
    'arm_neon%': '<(arm_neon)',
    'sysroot%': '<(sysroot)',
    'disable_sse2%': '<(disable_sse2)',

    # The release channel that this build targets. This is used to restrict
    # channel-specific build options, like which installer packages to create.
    # The default is 'all', which does no channel-specific filtering.
    'channel%': 'all',

    # Override chromium_mac_pch and set it to 0 to suppress the use of
    # precompiled headers on the Mac.  Prefix header injection may still be
    # used, but prefix headers will not be precompiled.  This is useful when
    # using distcc to distribute a build to compile slaves that don't
    # share the same compiler executable as the system driving the compilation,
    # because precompiled headers rely on pointers into a specific compiler
    # executable's image.  Setting this to 0 is needed to use an experimental
    # Linux-Mac cross compiler distcc farm.
    'chromium_mac_pch%': 1,

    # Mac OS X SDK and deployment target support.
    # The SDK identifies the version of the system headers that will be used,
    # and corresponds to the MAC_OS_X_VERSION_MAX_ALLOWED compile-time macro.
    # "Maximum allowed" refers to the operating system version whose APIs are
    # available in the headers.
    # The deployment target identifies the minimum system version that the
    # built products are expected to function on.  It corresponds to the
    # MAC_OS_X_VERSION_MIN_REQUIRED compile-time macro.
    # To ensure these macros are available, #include <AvailabilityMacros.h>.
    # Additional documentation on these macros is available at
    # http://developer.apple.com/mac/library/technotes/tn2002/tn2064.html#SECTION3
    # Chrome normally builds with the Mac OS X 10.5 SDK and sets the
    # deployment target to 10.5.  Other projects, such as O3D, may override
    # these defaults.
    'mac_sdk%': '10.5',
    'mac_deployment_target%': '10.5',

    # Set to 1 to enable code coverage.  In addition to build changes
    # (e.g. extra CFLAGS), also creates a new target in the src/chrome
    # project file called "coverage".
    # Currently ignored on Windows.
    'coverage%': 0,

    # Although base/allocator lets you select a heap library via an
    # environment variable, the libcmt shim it uses sometimes gets in
    # the way.  To disable it entirely, and switch to normal msvcrt, do e.g.
    #  'win_use_allocator_shim': 0,
    #  'win_release_RuntimeLibrary': 2
    # to ~/.gyp/include.gypi, gclient runhooks --force, and do a release build.
    'win_use_allocator_shim%': 1, # 0 = shim allocator via libcmt; 1 = msvcrt

    # Whether usage of OpenMAX is enabled.
    'enable_openmax%': 0,

    # TODO(bradnelson): eliminate this when possible.
    # To allow local gyp files to prevent release.vsprops from being included.
    # Yes(1) means include release.vsprops.
    # Once all vsprops settings are migrated into gyp, this can go away.
    'msvs_use_common_release%': 1,

    # TODO(bradnelson): eliminate this when possible.
    # To allow local gyp files to override additional linker options for msvs.
    # Yes(1) means set use the common linker options.
    'msvs_use_common_linker_extras%': 1,

    # TODO(sgk): eliminate this if possible.
    # It would be nicer to support this via a setting in 'target_defaults'
    # in chrome/app/locales/locales.gypi overriding the setting in the
    # 'Debug' configuration in the 'target_defaults' dict below,
    # but that doesn't work as we'd like.
    'msvs_debug_link_incremental%': '2',

    # This is the location of the sandbox binary. Chrome looks for this before
    # running the zygote process. If found, and SUID, it will be used to
    # sandbox the zygote process and, thus, all renderer processes.
    'linux_sandbox_path%': '',

    # Set this to true to enable SELinux support.
    'selinux%': 0,

    # Strip the binary after dumping symbols.
    'linux_strip_binary%': 0,

    # Enable TCMalloc.
    'linux_use_tcmalloc%': 1,

    # Disable TCMalloc's debugallocation.
    'linux_use_debugallocation%': 0,

    # Disable TCMalloc's heapchecker.
    'linux_use_heapchecker%': 0,

    # Set to 1 to turn on seccomp sandbox by default.
    # (Note: this is ignored for official builds.)
    'linux_use_seccomp_sandbox%': 0,

    # Set to select the Title Case versions of strings in GRD files.
    'use_titlecase_in_grd_files%': 0,

    # Used to disable Native Client at compile time, for platforms where it
    # isn't supported
    'disable_nacl%': 0,

    # Set Thumb compilation flags.
    'arm_thumb%': 0,

    # Set ARM fpu compilation flags (only meaningful if arm_version==7 and
    # arm_neon==0).
    'arm_fpu%': 'vfpv3',

    # Enable new NPDevice API.
    'enable_new_npdevice_api%': 0,

    'conditions': [
      ['OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
        # This will set gcc_version to XY if you are running gcc X.Y.*.
        # This is used to tweak build flags for gcc 4.4.
        'gcc_version%': '<!(python <(DEPTH)/build/compiler_version.py)',
        # Figure out the python architecture to decide if we build pyauto.
        'python_arch%': '<!(<(DEPTH)/build/linux/python_arch.sh <(sysroot)/usr/lib/libpython<(python_ver).so.1.0)',
        'linux_breakpad%': 1,
        'linux_dump_symbols%': 1,
      }],  # OS=="linux" or OS=="freebsd" or OS=="openbsd"
      ['OS=="mac"', {
        # Mac wants Title Case strings
        'use_titlecase_in_grd_files%': 1,
        'mac_breakpad%': 0,
        'mac_keystone%': 0,
      }],  # OS=="mac"
      # Whether to use multiple cores to compile with visual studio. This is
      # optional because it sometimes causes corruption on VS 2005.
      # It is on by default on VS 2008 and off on VS 2005.
      ['OS=="win"', {
        'conditions': [
          ['MSVS_VERSION=="2005"', {
            'msvs_multi_core_compile%': 0,
          },{
            'msvs_multi_core_compile%': 1,
          }],
          # Don't do incremental linking for large modules on 32-bit.
          ['MSVS_OS_BITS==32', {
            'msvs_large_module_debug_link_mode%': '1',  # No
          },{
            'msvs_large_module_debug_link_mode%': '2',  # Yes
          }],
        ],
        'nacl_win64_defines': [
          # This flag is used to minimize dependencies when building
          # Native Client loader for 64-bit Windows.
          'NACL_WIN64',
        ],
      }],
      # Compute based on OS and target architecture whether the GPU
      # plugin / process is supported.
      [ 'OS=="win" or (OS=="linux" and target_arch!="arm") or OS=="mac"', {
        # Enable a variable used elsewhere throughout the GYP files to determine
        # whether to compile in the sources for the GPU plugin / process.
        'enable_gpu%': 1,
      }, {  # GPU plugin not supported
        'enable_gpu%': 0,
      }],
      # Compute based on OS, target architecture and device whether GLES
      # is supported
      [ 'OS=="linux" and target_arch=="arm"', {
        # Enable a variable used elsewhere throughout the GYP files to determine
        # whether to compile in the sources for the GLES support.
        'enable_gles%': 1,
      }, {  # GLES not supported
        'enable_gles%': 0,
      }],
    ],

    # NOTE: When these end up in the Mac bundle, we need to replace '-' for '_'
    # so Cocoa is happy (http://crbug.com/20441).
    'locales': [
      'am', 'ar', 'bg', 'bn', 'ca', 'cs', 'da', 'de', 'el', 'en-GB',
      'en-US', 'es-419', 'es', 'et', 'fi', 'fil', 'fr', 'gu', 'he',
      'hi', 'hr', 'hu', 'id', 'it', 'ja', 'kn', 'ko', 'lt', 'lv',
      'ml', 'mr', 'nb', 'nl', 'pl', 'pt-BR', 'pt-PT', 'ro', 'ru',
      'sk', 'sl', 'sr', 'sv', 'sw', 'ta', 'te', 'th', 'tr', 'uk',
      'vi', 'zh-CN', 'zh-TW',
    ],
  },
  'target_defaults': {
    'variables': {
      # See http://gcc.gnu.org/onlinedocs/gcc-4.4.2/gcc/Optimize-Options.html
      'mac_release_optimization%': '3', # Use -O3 unless overridden
      'mac_debug_optimization%': '0',   # Use -O0 unless overridden
      # See http://msdn.microsoft.com/en-us/library/aa652360(VS.71).aspx
      'win_release_Optimization%': '2', # 2 = /Os
      'win_debug_Optimization%': '0',   # 0 = /Od
      # See http://msdn.microsoft.com/en-us/library/aa652367(VS.71).aspx
      'win_release_RuntimeLibrary%': '0', # 0 = /MT (nondebug static)
      'win_debug_RuntimeLibrary%': '1',   # 1 = /MTd (debug static)

      'release_extra_cflags%': '',
      'debug_extra_cflags%': '',
      'release_valgrind_build%': 0,
    },
    'conditions': [
      ['selinux==1', {
        'defines': ['CHROMIUM_SELINUX=1'],
      }],
      ['win_use_allocator_shim==0', {
        'conditions': [
          ['OS=="win"', {
            'defines': ['NO_TCMALLOC'],
          }],
        ],
      }],
      ['enable_gpu==1', {
        'defines': [
          'ENABLE_GPU=1',
        ],
      }],
      ['enable_gles==1', {
        'defines': [
          'ENABLE_GLES=1',
        ],
      }],
      ['coverage!=0', {
        'conditions': [
          ['OS=="mac"', {
            'xcode_settings': {
              'GCC_INSTRUMENT_PROGRAM_FLOW_ARCS': 'YES',  # -fprofile-arcs
              'GCC_GENERATE_TEST_COVERAGE_FILES': 'YES',  # -ftest-coverage
            },
            # Add -lgcov for types executable, shared_library, and
            # loadable_module; not for static_library.
            # This is a delayed conditional.
            'target_conditions': [
              ['_type!="static_library"', {
                'xcode_settings': { 'OTHER_LDFLAGS': [ '-lgcov' ] },
              }],
            ],
          }],
          # Linux gyp (into scons) doesn't like target_conditions?
          # TODO(???): track down why 'target_conditions' doesn't work
          # on Linux gyp into scons like it does on Mac gyp into xcodeproj.
          ['OS=="linux"', {
            'cflags': [ '-ftest-coverage',
                        '-fprofile-arcs' ],
            'link_settings': { 'libraries': [ '-lgcov' ] },
          }],
          # Finally, for Windows, we simply turn on profiling.
          ['OS=="win"', {
            'msvs_settings': {
              'VCLinkerTool': {
                'Profile': 'true',
              },
              'VCCLCompilerTool': {
                # /Z7, not /Zi, so coverage is happyb
                'DebugInformationFormat': '1',
                'AdditionalOptions': ['/Yd'],
              }
            }
         }],  # OS==win
        ],  # conditions for coverage
      }],  # coverage!=0
    ],  # conditions for 'target_defaults'
    'target_conditions': [
      [ 'OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
        'cflags!': [
          '-Wall',
          '-Wextra',
          '-Werror',
        ],
      }],
      [ 'OS=="win"', {
        'defines': [
          '_CRT_SECURE_NO_DEPRECATE',
          '_CRT_NONSTDC_NO_WARNINGS',
          '_CRT_NONSTDC_NO_DEPRECATE',
          # This is required for ATL to use XP-safe versions of its functions.
          '_USING_V110_SDK71_',
        ],
        'msvs_disabled_warnings': [4800],
        'msvs_settings': {
          'VCCLCompilerTool': {
            'WarnAsError': 'true',
            'Detect64BitPortabilityProblems': 'false',
          },
        },
      }],
      [ 'OS=="mac"', {
        'xcode_settings': {
          'GCC_TREAT_WARNINGS_AS_ERRORS': 'NO',
          'WARNING_CFLAGS!': ['-Wall'],
        },
      }],
    ],  # target_conditions for 'target_defaults'
    'default_configuration': 'Debug',
    'configurations': {
      # VCLinkerTool LinkIncremental values below:
      #   0 == default
      #   1 == /INCREMENTAL:NO
      #   2 == /INCREMENTAL
      # Debug links incremental, Release does not.
      #
      # Abstract base configurations to cover common
      # attributes.
      #
      'Common_Base': {
        'abstract': 1,
        'msvs_configuration_attributes': {
          'OutputDirectory': '$(SolutionDir)$(ConfigurationName)',
          'IntermediateDirectory': '$(OutDir)\\obj\\$(ProjectName)',
          'CharacterSet': '1',
        },
      },
      'x86_Base': {
        'abstract': 1,
        'msvs_settings': {
          'VCLinkerTool': {
            'MinimumRequiredVersion': '5.01',  # XP.
            'TargetMachine': '1',
          },
        },
        'msvs_configuration_platform': 'Win32',
      },
      'x64_Base': {
        'abstract': 1,
        'msvs_configuration_platform': 'x64',
        'msvs_settings': {
          'VCLinkerTool': {
            'TargetMachine': '17', # x86 - 64
            'AdditionalLibraryDirectories!':
              ['<(DEPTH)/third_party/platformsdk_win7/files/Lib'],
            'AdditionalLibraryDirectories':
              ['<(DEPTH)/third_party/platformsdk_win7/files/Lib/x64'],
          },
          'VCLibrarianTool': {
            'AdditionalLibraryDirectories!':
              ['<(DEPTH)/third_party/platformsdk_win7/files/Lib'],
            'AdditionalLibraryDirectories':
              ['<(DEPTH)/third_party/platformsdk_win7/files/Lib/x64'],
          },
        },
        'defines': [
          # Not sure if tcmalloc works on 64-bit Windows.
          'NO_TCMALLOC',
        ],
      },
      'Debug_Base': {
        'abstract': 1,
        'xcode_settings': {
          'COPY_PHASE_STRIP': 'NO',
          'GCC_OPTIMIZATION_LEVEL': '<(mac_debug_optimization)',
          'OTHER_CFLAGS': [ '<@(debug_extra_cflags)', ],
        },
        'msvs_settings': {
          'VCCLCompilerTool': {
            'Optimization': '<(win_debug_Optimization)',
            'PreprocessorDefinitions': ['_DEBUG'],
            'BasicRuntimeChecks': '3',
            'RuntimeLibrary': '<(win_debug_RuntimeLibrary)',
          },
          'VCLinkerTool': {
            'LinkIncremental': '<(msvs_debug_link_incremental)',
          },
          'VCResourceCompilerTool': {
            'PreprocessorDefinitions': ['_DEBUG'],
          },
        },
        'conditions': [
          ['OS=="linux"', {
            'cflags': [
              '<@(debug_extra_cflags)',
            ],
          }],
        ],
      },
      'Release_Base': {
        'abstract': 1,
        'defines': [
          'NDEBUG',
        ],
        'xcode_settings': {
          'DEAD_CODE_STRIPPING': 'YES',  # -Wl,-dead_strip
          'GCC_OPTIMIZATION_LEVEL': '<(mac_release_optimization)',
          'OTHER_CFLAGS': [ '<@(release_extra_cflags)', ],
        },
        'msvs_settings': {
          'VCCLCompilerTool': {
            'Optimization': '<(win_release_Optimization)',
            'RuntimeLibrary': '<(win_release_RuntimeLibrary)',
          },
          'VCLinkerTool': {
            'LinkIncremental': '1',
          },
        },
        'conditions': [
          ['release_valgrind_build==0', {
            'defines': ['NVALGRIND'],
          }],
          ['win_use_allocator_shim==0', {
            'defines': ['NO_TCMALLOC'],
          }],
          ['win_release_RuntimeLibrary==2', {
            # Visual C++ 2008 barfs when building anything with /MD (msvcrt):
            #  VC\include\typeinfo(139) : warning C4275: non dll-interface
            #  class 'stdext::exception' used as base for dll-interface
            #  class 'std::bad_cast'
            'msvs_disabled_warnings': [4275],
          }],
          ['OS=="linux"', {
            'cflags': [
             '<@(release_extra_cflags)',
            ],
          }],
        ],
      },
      'Purify_Base': {
        'abstract': 1,
        'defines': [
          'PURIFY',
          'NO_TCMALLOC',
        ],
        'msvs_settings': {
          'VCCLCompilerTool': {
            'Optimization': '0',
            'RuntimeLibrary': '0',
            'BufferSecurityCheck': 'false',
          },
          'VCLinkerTool': {
            'EnableCOMDATFolding': '1',
            'LinkIncremental': '1',
          },
        },
      },
      #
      # Concrete configurations
      #
      'Debug': {
        'inherit_from': ['Common_Base', 'x86_Base', 'Debug_Base'],
      },
      'Release': {
        'inherit_from': ['Common_Base', 'x86_Base', 'Release_Base'],
        'conditions': [
          ['msvs_use_common_release', {
            'defines': ['OFFICIAL_BUILD'],
            'msvs_settings': {
              'VCCLCompilerTool': {
                'Optimization': '3',
                'StringPooling': 'true',
                'OmitFramePointers': 'true',
                'InlineFunctionExpansion': '2',
                'EnableIntrinsicFunctions': 'true',
                'FavorSizeOrSpeed': '2',
                'OmitFramePointers': 'true',
                'EnableFiberSafeOptimizations': 'true',
                'WholeProgramOptimization': 'true',
              },
              'VCLibrarianTool': {
                'AdditionalOptions': ['/ltcg', '/expectedoutputsize:120000000'],
              },
              'VCLinkerTool': {
                'LinkIncremental': '1',
                'OptimizeReferences': '2',
                'EnableCOMDATFolding': '2',
                'OptimizeForWindows98': '1',
                'LinkTimeCodeGeneration': '1',
              },
            },
          }],
        ]
      },
      'conditions': [
        [ 'OS=="win"', {
          # TODO(bradnelson): add a gyp mechanism to make this more graceful.
          'Purify': {
            'inherit_from': ['Common_Base', 'x86_Base', 'Release_Base', 'Purify'],
          },
          'Debug_x64': {
            'inherit_from': ['Common_Base', 'x64_Base', 'Debug_Base'],
          },
          'Release_x64': {
            'inherit_from': ['Common_Base', 'x64_Base', 'Release_Base'],
          },
          'Purify_x64': {
            'inherit_from': ['Common_Base', 'x64_Base', 'Release_Base', 'Purify_Base'],
          },
        }],
      ],
    },
  },
  'conditions': [
    ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris"', {
      'target_defaults': {
        # Enable -Werror by default, but put it in a variable so it can
        # be disabled in ~/.gyp/include.gypi on the valgrind builders.
        'variables': {
          # Use -fno-strict-aliasing by default since gcc 4.4 has periodic
          # issues that slip through the cracks. We could do this just for
          # gcc 4.4 but it makes more sense to be consistent on all
          # compilers in use. TODO(Craig): turn this off again when
          # there is some 4.4 test infrastructure in place and existing
          # aliasing issues have been fixed.
          'no_strict_aliasing%': 1,
          'conditions': [['OS=="linux"', {'werror%': '-Werror',}],
                         ['OS=="freebsd"', {'werror%': '',}],
                         ['OS=="openbsd"', {'werror%': '',}],
          ],
        },
        'cflags': [
          '<(werror)',  # See note above about the werror variable.
          '-pthread',
          '-fno-exceptions',
          '-Wall',
          # TODO(evan): turn this back on once all the builds work.
          # '-Wextra',
          # Don't warn about unused function params.  We use those everywhere.
          '-Wno-unused-parameter',
          # Don't warn about the "struct foo f = {0};" initialization pattern.
          '-Wno-missing-field-initializers',
          '-D_FILE_OFFSET_BITS=64',
          # Don't export any symbols (for example, to plugins we dlopen()).
          # Note: this is *required* to make some plugins work.
          '-fvisibility=hidden',
        ],
        'cflags_cc': [
          '-fno-rtti',
          '-fno-threadsafe-statics',
          # Make inline functions have hidden visiblity by default.
          # Surprisingly, not covered by -fvisibility=hidden.
          '-fvisibility-inlines-hidden',
        ],
        'ldflags': [
          '-pthread', '-Wl,-z,noexecstack',
        ],
        'scons_variable_settings': {
          'LIBPATH': ['$LIB_DIR'],
          # Linking of large files uses lots of RAM, so serialize links
          # using the handy flock command from util-linux.
          'FLOCK_LINK': ['flock', '$TOP_BUILDDIR/linker.lock', '$LINK'],
          'FLOCK_SHLINK': ['flock', '$TOP_BUILDDIR/linker.lock', '$SHLINK'],
          'FLOCK_LDMODULE': ['flock', '$TOP_BUILDDIR/linker.lock', '$LDMODULE'],

          # We have several cases where archives depend on each other in
          # a cyclic fashion.  Since the GNU linker does only a single
          # pass over the archives we surround the libraries with
          # --start-group and --end-group (aka -( and -) ). That causes
          # ld to loop over the group until no more undefined symbols
          # are found. In an ideal world we would only make groups from
          # those libraries which we knew to be in cycles. However,
          # that's tough with SCons, so we bodge it by making all the
          # archives a group by redefining the linking command here.
          #
          # TODO:  investigate whether we still have cycles that
          # require --{start,end}-group.  There has been a lot of
          # refactoring since this was first coded, which might have
          # eliminated the circular dependencies.
          #
          # Note:  $_LIBDIRFLAGS comes before ${LINK,SHLINK,LDMODULE}FLAGS
          # so that we prefer our own built libraries (e.g. -lpng) to
          # system versions of libraries that pkg-config might turn up.
          # TODO(sgk): investigate handling this not by re-ordering the
          # flags this way, but by adding a hook to use the SCons
          # ParseFlags() option on the output from pkg-config.
          'LINKCOM': [['$FLOCK_LINK', '-o', '$TARGET',
                       '$_LIBDIRFLAGS', '$LINKFLAGS', '$SOURCES',
                       '-Wl,--start-group', '$_LIBFLAGS', '-Wl,--end-group']],
          'SHLINKCOM': [['$FLOCK_SHLINK', '-o', '$TARGET',
                         '$_LIBDIRFLAGS', '$SHLINKFLAGS', '$SOURCES',
                         '-Wl,--start-group', '$_LIBFLAGS', '-Wl,--end-group']],
          'LDMODULECOM': [['$FLOCK_LDMODULE', '-o', '$TARGET',
                           '$_LIBDIRFLAGS', '$LDMODULEFLAGS', '$SOURCES',
                           '-Wl,--start-group', '$_LIBFLAGS', '-Wl,--end-group']],
          'IMPLICIT_COMMAND_DEPENDENCIES': 0,
          # -rpath is only used when building with shared libraries.
          'conditions': [
            [ 'component=="shared_library"', {
              'RPATH': '$LIB_DIR',
            }],
          ],
        },
        'scons_import_variables': [
          'AS',
          'CC',
          'CXX',
          'LINK',
        ],
        'scons_propagate_variables': [
          'AS',
          'CC',
          'CCACHE_DIR',
          'CXX',
          'DISTCC_DIR',
          'DISTCC_HOSTS',
          'HOME',
          'INCLUDE_SERVER_ARGS',
          'INCLUDE_SERVER_PORT',
          'LINK',
          'CHROME_BUILD_TYPE',
          'CHROMIUM_BUILD',
          'OFFICIAL_BUILD',
        ],
        'configurations': {
          'Debug_Base': {
            'variables': {
              'debug_optimize%': '0',
            },
            'defines': [
              '_DEBUG',
            ],
            'cflags': [
              '-O>(debug_optimize)',
              '-g',
              # One can use '-gstabs' to enable building the debugging
              # information in STABS format for breakpad's dumpsyms.
            ],
            'ldflags': [
              '-rdynamic',  # Allows backtrace to resolve symbols.
            ],
          },
          'Release_Base': {
            'variables': {
              'release_optimize%': '2',
            },
            'cflags': [
              '-O>(release_optimize)',
              # Don't emit the GCC version ident directives, they just end up
              # in the .comment section taking up binary size.
              '-fno-ident',
              # Put data and code in their own sections, so that unused symbols
              # can be removed at link time with --gc-sections.
              '-fdata-sections',
              '-ffunction-sections',
            ],
            'ldflags': [
              '-Wl,--gc-sections',
            ],
          },
        },
        'variants': {
          'coverage': {
            'cflags': ['-fprofile-arcs', '-ftest-coverage'],
            'ldflags': ['-fprofile-arcs'],
          },
          'profile': {
            'cflags': ['-pg', '-g'],
            'ldflags': ['-pg'],
          },
          'symbols': {
            'cflags': ['-g'],
          },
        },
        'conditions': [
          [ 'target_arch=="ia32"', {
            'asflags': [
              # Needed so that libs with .s files (e.g. libicudata.a)
              # are compatible with the general 32-bit-ness.
              '-32',
            ],
            # All floating-point computations on x87 happens in 80-bit
            # precision.  Because the C and C++ language standards allow
            # the compiler to keep the floating-point values in higher
            # precision than what's specified in the source and doing so
            # is more efficient than constantly rounding up to 64-bit or
            # 32-bit precision as specified in the source, the compiler,
            # especially in the optimized mode, tries very hard to keep
            # values in x87 floating-point stack (in 80-bit precision)
            # as long as possible. This has important side effects, that
            # the real value used in computation may change depending on
            # how the compiler did the optimization - that is, the value
            # kept in 80-bit is different than the value rounded down to
            # 64-bit or 32-bit. There are possible compiler options to make
            # this behavior consistent (e.g. -ffloat-store would keep all
            # floating-values in the memory, thus force them to be rounded
            # to its original precision) but they have significant runtime
            # performance penalty.
            #
            # -mfpmath=sse -msse2 makes the compiler use SSE instructions
            # which keep floating-point values in SSE registers in its
            # native precision (32-bit for single precision, and 64-bit for
            # double precision values). This means the floating-point value
            # used during computation does not change depending on how the
            # compiler optimized the code, since the value is always kept
            # in its specified precision.
            'conditions': [
              ['disable_sse2==0', {
                'cflags': [
                  '-march=pentium4',
                  '-msse2',
                  '-mfpmath=sse',
                ],
              }],
            ],
            # -mmmx allows mmintrin.h to be used for mmx intrinsics.
            # video playback is mmx and sse2 optimized.
            'cflags': [
              '-m32',
              '-mmmx',
            ],
            'ldflags': [
              '-m32',
            ],
          }],
          ['target_arch=="arm"', {
            'target_conditions': [
              ['_toolset=="target"', {
                'cflags_cc': [
                  # The codesourcery arm-2009q3 toolchain warns at that the ABI
                  # has changed whenever it encounters a varargs function. This
                  # silences those warnings, as they are not helpful and
                  # clutter legitimate warnings.
                  '-Wno-abi',
                ],
                'conditions': [
                  ['arm_thumb == 1', {
                    'cflags': [
                    '-mthumb',
                    # TODO(piman): -Wa,-mimplicit-it=thumb is needed for
                    # inline assembly that uses condition codes but it's
                    # suboptimal. Better would be to #ifdef __thumb__ at the
                    # right place and have a separate thumb path.
                    '-Wa,-mimplicit-it=thumb',
                    ]
                  }],
                  ['arm_version==7', {
                    'cflags': [
                      '-march=armv7-a',
                      '-mtune=cortex-a8',
                      '-mfloat-abi=softfp',
                    ],
                    'conditions': [
                      ['arm_neon==1', {
                        'cflags': [ '-mfpu=neon', ],
                      }, {
                        'cflags': [ '-mfpu=<(arm_fpu)', ],
                      }]
                    ],
                  }],
                ],
              }],
            ],
          }],
          ['linux_fpic==1', {
            'cflags': [
              '-fPIC',
            ],
          }],
          ['sysroot!=""', {
            'target_conditions': [
              ['_toolset=="target"', {
                'cflags': [
                  '--sysroot=<(sysroot)',
                ],
                'ldflags': [
                  '--sysroot=<(sysroot)',
                ],
              }]]
          }],
          ['no_strict_aliasing==1', {
            'cflags': [
              '-fno-strict-aliasing',
            ],
          }],
          ['linux_breakpad==1', {
            'cflags': [ '-gstabs' ],
            'defines': ['USE_LINUX_BREAKPAD'],
          }],
          ['library=="shared_library"', {
            # When building with shared libraries, remove the visiblity-hiding
            # flag.
            'cflags!': [ '-fvisibility=hidden' ],
            'conditions': [
              ['target_arch=="x64" or target_arch=="arm"', {
                # Shared libraries need -fPIC on x86-64 and arm
                'cflags': ['-fPIC']
              }]
            ],
          }],
          ['linux_use_heapchecker==1', {
            'variables': {'linux_use_tcmalloc%': 1},
          }],
          ['linux_use_tcmalloc==0', {
            'defines': ['NO_TCMALLOC'],
          }],
          ['linux_use_heapchecker==0', {
            'defines': ['NO_HEAPCHECKER'],
          }],
        ],
      },
    }],
    # FreeBSD-specific options; note that most FreeBSD options are set above,
    # with Linux.
    ['OS=="freebsd"', {
      'target_defaults': {
        'ldflags': [
          '-Wl,--no-keep-memory',
        ],
      },
    }],
    ['OS=="solaris"', {
      'cflags!': ['-fvisibility=hidden'],
      'cflags_cc!': ['-fvisibility-inlines-hidden'],
    }],
    ['OS=="mac"', {
      'target_defaults': {
        'variables': {
          # This should be 'mac_real_dsym%', but there seems to be a bug
          # with % in variables that are intended to be set to different
          # values in different targets, like this one.
          'mac_real_dsym': 0,  # Fake .dSYMs are fine in most cases.
        },
        'mac_bundle': 0,
        'xcode_settings': {
          'ALWAYS_SEARCH_USER_PATHS': 'NO',
          'GCC_C_LANGUAGE_STANDARD': 'c99',         # -std=c99
          'GCC_CW_ASM_SYNTAX': 'NO',                # No -fasm-blocks
          'GCC_DYNAMIC_NO_PIC': 'NO',               # No -mdynamic-no-pic
                                                    # (Equivalent to -fPIC)
          'GCC_ENABLE_CPP_EXCEPTIONS': 'NO',        # -fno-exceptions
          'GCC_ENABLE_CPP_RTTI': 'NO',              # -fno-rtti
          'GCC_ENABLE_PASCAL_STRINGS': 'NO',        # No -mpascal-strings
          # GCC_INLINES_ARE_PRIVATE_EXTERN maps to -fvisibility-inlines-hidden
          'GCC_INLINES_ARE_PRIVATE_EXTERN': 'YES',
          'GCC_OBJC_CALL_CXX_CDTORS': 'YES',        # -fobjc-call-cxx-cdtors
          'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES',      # -fvisibility=hidden
          'GCC_THREADSAFE_STATICS': 'NO',           # -fno-threadsafe-statics
          'GCC_TREAT_WARNINGS_AS_ERRORS': 'YES',    # -Werror
          'GCC_VERSION': '4.2',
          'GCC_WARN_ABOUT_MISSING_NEWLINE': 'YES',  # -Wnewline-eof
          # MACOSX_DEPLOYMENT_TARGET maps to -mmacosx-version-min
          'MACOSX_DEPLOYMENT_TARGET': '<(mac_deployment_target)',
          'PREBINDING': 'NO',                       # No -Wl,-prebind
          'USE_HEADERMAP': 'NO',
          'WARNING_CFLAGS': ['-Wall', '-Wendif-labels'],
          'conditions': [
            ['chromium_mac_pch', {'GCC_PRECOMPILE_PREFIX_HEADER': 'YES'},
                                 {'GCC_PRECOMPILE_PREFIX_HEADER': 'NO'}
            ],
          ],
        },
        'target_conditions': [
          ['_type!="static_library"', {
            'xcode_settings': {'OTHER_LDFLAGS': ['-Wl,-search_paths_first']},
          }],
          ['_mac_bundle', {
            'xcode_settings': {'OTHER_LDFLAGS': ['-Wl,-ObjC']},
          }],
          ['_type=="executable" or _type=="shared_library"', {
            'target_conditions': [
              ['mac_real_dsym == 1', {
                # To get a real .dSYM bundle produced by dsymutil, set the
                # debug information format to dwarf-with-dsym.  Since
                # strip_from_xcode will not be used, set Xcode to do the
                # stripping as well.
                'configurations': {
                  'Release_Base': {
                    'xcode_settings': {
                      'DEBUG_INFORMATION_FORMAT': 'dwarf-with-dsym',
                      'DEPLOYMENT_POSTPROCESSING': 'YES',
                      'STRIP_INSTALLED_PRODUCT': 'YES',
                      'target_conditions': [
                        ['_type=="shared_library"', {
                          # The Xcode default is to strip debugging symbols
                          # only (-S).  Local symbols should be stripped as
                          # well, which will be handled by -x.  Xcode will
                          # continue to insert -S when stripping even when
                          # additional flags are added with STRIPFLAGS.
                          'STRIPFLAGS': '-x',
                        }],  # _type=="shared_library"
                      ],  # target_conditions
                    },  # xcode_settings
                  },  # configuration "Release"
                },  # configurations
              }, {  # mac_real_dsym != 1
                # To get a fast fake .dSYM bundle, use a post-build step to
                # produce the .dSYM and strip the executable.  strip_from_xcode
                # only operates in the Release configuration.
                'postbuilds': [
                  {
                    'variables': {
                      # Define strip_from_xcode in a variable ending in _path
                      # so that gyp understands it's a path and performs proper
                      # relativization during dict merging.
                      'strip_from_xcode_path': 'mac/strip_from_xcode',
                    },
                    'postbuild_name': 'Strip If Needed',
                    'action': ['<(strip_from_xcode_path)'],
                  },
                ],  # postbuilds
              }],  # mac_real_dsym
            ],  # target_conditions
          }],  # _type=="executable" or _type=="shared_library"
        ],  # target_conditions
      },  # target_defaults
    }],  # OS=="mac"
    ['OS=="win"', {
      'target_defaults': {
        'defines': [
          '_WIN32_WINNT=0x0600',
          'WINVER=0x0600',
          'WIN32',
          '_WINDOWS',
          '_HAS_EXCEPTIONS=0',
          'NOMINMAX',
          '_CRT_RAND_S',
          'CERT_CHAIN_PARA_HAS_EXTRA_FIELDS',
          'WIN32_LEAN_AND_MEAN',
          '_SECURE_ATL',
          '_HAS_TR1=0',
        ],
        'msvs_system_include_dirs': [
          '<(DEPTH)/third_party/platformsdk_win7/files/Include',
          '$(VSInstallDir)/VC/atlmfc/include',
        ],
        'msvs_cygwin_dirs': ['<(DEPTH)/third_party/cygwin'],
        'msvs_disabled_warnings': [
          4100, 4127, 4396, 4503, 4512, 4819, 4995, 4702
        ],
        'msvs_settings': {
          'VCCLCompilerTool': {
            'MinimalRebuild': 'false',
            'ExceptionHandling': '0',
            'BufferSecurityCheck': 'true',
            'EnableFunctionLevelLinking': 'true',
            'RuntimeTypeInfo': 'false',
            'WarningLevel': '4',
            'WarnAsError': 'true',
            'DebugInformationFormat': '3',
            'conditions': [
              [ 'msvs_multi_core_compile', {
                'AdditionalOptions': ['/MP'],
              }],
            ],
          },
          'VCLibrarianTool': {
            'AdditionalOptions': ['/ignore:4221'],
            'AdditionalLibraryDirectories':
              ['<(DEPTH)/third_party/platformsdk_win7/files/Lib'],
          },
          'VCLinkerTool': {
            'AdditionalDependencies': [
              'wininet.lib',
              'version.lib',
              'msimg32.lib',
              'ws2_32.lib',
              'usp10.lib',
              'psapi.lib',
              'dbghelp.lib',
            ],
            'AdditionalLibraryDirectories':
              ['<(DEPTH)/third_party/platformsdk_win7/files/Lib'],
            'GenerateDebugInformation': 'true',
            'MapFileName': '$(OutDir)\\$(TargetName).map',
            'ImportLibrary': '$(OutDir)\\lib\\$(TargetName).lib',
            'FixedBaseAddress': '1',
            # SubSystem values:
            #   0 == not set
            #   1 == /SUBSYSTEM:CONSOLE
            #   2 == /SUBSYSTEM:WINDOWS
            # Most of the executables we'll ever create are tests
            # and utilities with console output.
            'SubSystem': '1',
          },
          'VCMIDLTool': {
            'GenerateStublessProxies': 'true',
            'TypeLibraryName': '$(InputName).tlb',
            'OutputDirectory': '$(IntDir)',
            'HeaderFileName': '$(InputName).h',
            'DLLDataFileName': 'dlldata.c',
            'InterfaceIdentifierFileName': '$(InputName)_i.c',
            'ProxyFileName': '$(InputName)_p.c',
          },
          'VCResourceCompilerTool': {
            'Culture' : '1033',
            'AdditionalIncludeDirectories': ['<(DEPTH)'],
          },
        },
      },
    }],
    ['disable_nacl==1 or OS=="freebsd" or OS=="openbsd" or OS=="solaris"', {
      'target_defaults': {
        'defines': [
          'DISABLE_NACL',
        ],
      },
    }],
    ['OS=="win" and msvs_use_common_linker_extras', {
      'target_defaults': {
        'msvs_settings': {
          'VCLinkerTool': {
            'DelayLoadDLLs': [
              'dbghelp.dll',
              'dwmapi.dll',
              'uxtheme.dll',
            ],
          },
        },
        'configurations': {
          'x86_Base': {
            'msvs_settings': {
              'VCLinkerTool': {
                'AdditionalOptions': [
                  '/safeseh',
                  '/dynamicbase',
                  '/ignore:4199',
                  '/ignore:4221',
                  '/nxcompat',
                ],
              },
            },
          },
          'x64_Base': {
            'msvs_settings': {
              'VCLinkerTool': {
                'AdditionalOptions': [
                  # safeseh is not compatible with x64
                  '/dynamicbase',
                  '/ignore:4199',
                  '/ignore:4221',
                  '/nxcompat',
                ],
              },
            },
          },
        },
      },
    }],
    ['enable_new_npdevice_api==1', {
      'target_defaults': {
        'defines': [
          'ENABLE_NEW_NPDEVICE_API',
        ],
      },
    }],
  ],
  'scons_settings': {
    'sconsbuild_dir': '<(DEPTH)/sconsbuild',
    'tools': ['ar', 'as', 'gcc', 'g++', 'gnulink', 'chromium_builders'],
  },
  'xcode_settings': {
    # DON'T ADD ANYTHING NEW TO THIS BLOCK UNLESS YOU REALLY REALLY NEED IT!
    # This block adds *project-wide* configuration settings to each project
    # file.  It's almost always wrong to put things here.  Specify your
    # custom xcode_settings in target_defaults to add them to targets instead.

    # In an Xcode Project Info window, the "Base SDK for All Configurations"
    # setting sets the SDK on a project-wide basis.  In order to get the
    # configured SDK to show properly in the Xcode UI, SDKROOT must be set
    # here at the project level.
    'SDKROOT': 'macosx<(mac_sdk)',  # -isysroot

    # The Xcode generator will look for an xcode_settings section at the root
    # of each dict and use it to apply settings on a file-wide basis.  Most
    # settings should not be here, they should be in target-specific
    # xcode_settings sections, or better yet, should use non-Xcode-specific
    # settings in target dicts.  SYMROOT is a special case, because many other
    # Xcode variables depend on it, including variables such as
    # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
    # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
    # files to appear (when present) in the UI as actual files and not red
    # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
    # and therefore SYMROOT, needs to be set at the project level.
    'SYMROOT': '<(DEPTH)/xcodebuild',
  },
}