Populating is_multiple in google_breakpad::StackFrame from symbol files.

This is needed in order to properly detect and highlight frames that
correspond to multiple functions, for example as the result of identical
code folding by the linker.

Bug: google-breakpad:751
Change-Id: I2ee7c147fcff6493c2454383ad5422b38269759a
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/3471034
Reviewed-by: Joshua Peraza <jperaza@chromium.org>

src/google_breakpad/processor/stack_frame.h

@@ -63,7 +63,8 @@ struct StackFrame {
         source_file_name(),
         source_line(0),
         source_line_base(),
-        trust(FRAME_TRUST_NONE){}
+        trust(FRAME_TRUST_NONE),
+        is_multiple(false) {}
   virtual ~StackFrame() {}
 
   // Return a string describing how this stack frame was found
@@ -140,6 +141,12 @@ struct StackFrame {
   // Amount of trust the stack walker has in the instruction pointer
   // of this frame.
   FrameTrust trust;
+
+  // True if the frame corresponds to multiple functions, for example as the
+  // result of identical code folding by the linker. In that case the function
+  // name, filename, etc. information above represents the state of an arbitrary
+  // one of these functions.
+  bool is_multiple;
 };
 
 }  // namespace google_breakpad