Support vtable_verify (new compiler option).

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 3f64fa96e10e8cb83e6fac866efed49dcd81935c..508c53013ed9c26d26f0e1c14458293342fae2e7 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -387,6 +387,10 @@
       'sas_dll_path%': '<(DEPTH)/third_party/platformsdk_win7/files/redist/x86',
       'wix_path%': '<(DEPTH)/third_party/wix',
 
+      # Whether or not to turn on vtable verification hardening.

[Mark Mentovai, 2012/08/13 20:07:12]

Do you need this? Can you get rid of it and move the comment and default 0 value
down to the enclosing scope?

+      'use_vtable_verify%': 0,
+
+
       'conditions': [
         # TODO(epoger): Figure out how to set use_skia=1 for Mac outside of
         # the 'conditions' clause.  Initial attempts resulted in chromium and
@@ -615,6 +619,7 @@
     'android_upstream_bringup%': '<(android_upstream_bringup)',
     'use_system_libjpeg%': '<(use_system_libjpeg)',
     'android_build_type%': '<(android_build_type)',
+    'use_vtable_verify%': '<(use_vtable_verify)',
 
     # Use system yasm instead of bundled one.
     'use_system_yasm%': 0,
@@ -1219,6 +1224,11 @@
         'use_system_zlib': 0,
       }],
 
+      ['use_vtable_verify==1', {
+       'debug_extra_cflags': '-fvtable-verify=std',

[Mark Mentovai, 2012/08/13 20:07:12]

Fix up weird indentation here too.

+       'release_extra_cflags': '-fvtable-verify=std',
+       }],
+
       # Build tweaks for DrMemory.
       # TODO(rnk): Combine with tsan config to share the builder.
       # http://crbug.com/108155