Support vtable_verify (new compiler option).

base/allocator/allocator.gyp

Index: base/allocator/allocator.gyp
diff --git a/base/allocator/allocator.gyp b/base/allocator/allocator.gyp
index e2c8ac0faeb383fd96b138b1f99b23c830ab21bb..4e9f4aaf4e698ee04982d691f6368f5a1e1710e4 100644
--- a/base/allocator/allocator.gyp
+++ b/base/allocator/allocator.gyp
@@ -6,6 +6,7 @@
   'variables': {
     'jemalloc_dir': '../../third_party/jemalloc/chromium',
     'tcmalloc_dir': '../../third_party/tcmalloc/chromium',
+    'use_vtable_verify%': 0,
   },
   'targets': [
     {
@@ -394,6 +395,13 @@
               '-Wl,-u_ZN15HeapLeakChecker12IgnoreObjectEPKv,-u_ZN15HeapLeakChecker14UnIgnoreObjectEPKv',
           ]},
         }],
+        [ 'use_vtable_verify==1', {
+          'cflags': [
+            '-Wno-sign-compare',

[Mark Mentovai, 2012/08/16 18:05:09]

OS==linux already sets -Wno-sign-compare and -Wno-unused-result above on lines
381 and 382. These two are extraneous here. cflags are additive. You can remove
these.

+            '-Wno-unused-result',
+            '-fvtable-verify=preinit',
+          ],
+        }],
         [ 'linux_use_debugallocation==1', {
           'sources!': [
             # debugallocation.cc #includes tcmalloc.cc,