More robust stack walks when the IP address in the context frame is invalid (or not in a known module).

This is achieved by:
1. Extending the span of the scan for return address in the conext frame.  Initially, I wanted to extend the span of the scan for all frames but then I noticed that there is code for ARM already that is extending the search only for the context frame.  This kind of makes sense so I decided to reuse the same idea everywhere.
2. Attempting to restore the EBP chain after a successful scan for return address so that the stackwalker can switch back to FRAME_TRUST_CFI for the rest of the frames when possible.

I also fixed the lint errors in the files touched.
Review URL: https://breakpad.appspot.com/605002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1193 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 9 insertions, 2 deletions

diff --git a/src/google_breakpad/processor/stackwalker.h b/src/google_breakpad/processor/stackwalker.h
index 3640cc73..11039d6e 100644
--- a/src/google_breakpad/processor/stackwalker.h
+++ b/src/google_breakpad/processor/stackwalker.h
@@ -126,9 +126,16 @@ class Stackwalker {
   template<typename InstructionType>
   bool ScanForReturnAddress(InstructionType location_start,
                             InstructionType* location_found,
-                            InstructionType* ip_found) {
+                            InstructionType* ip_found,
+                            bool is_context_frame) {
+    // When searching for the caller of the context frame,
+    // allow the scanner to look farther down the stack.
+    const int search_words = is_context_frame ?
+      kRASearchWords * 4 :
+      kRASearchWords;
+
     return ScanForReturnAddress(location_start, location_found, ip_found,
-                                kRASearchWords);
+                                search_words);
   }
 
   // Scan the stack starting at location_start, looking for an address