clang/win: Enable -Woverloaded-virtual globally.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 3125 matching lines @@
       ['<(chromeos)==1 and >(nacl_untrusted_build)==0', {
         'defines': ['OS_CHROMEOS=1'],
       }],
       ['enable_wexit_time_destructors==1 and OS!="win"', {
         # TODO: Enable on Windows too, http://crbug.com/404525
         'variables': { 'clang_warning_flags': ['-Wexit-time-destructors']},
       }],
       ['chromium_code==0', {
         'variables': {
           'clang_warning_flags': [
-            # TODO(mgiuca): Move this suppression into individual third-party
-            # libraries as required. http://crbug.com/505301.
-            '-Wno-overloaded-virtual',
             # TODO(thakis): Move this suppression into individual third-party
             # libraries as required. http://crbug.com/505316.
             '-Wno-unused-function',
             # Lots of third-party libraries have unused variables. Instead of
             # suppressing them individually, we just blanket suppress them here.
             '-Wno-unused-variable',
           ],
         },
         'conditions': [
           [ 'os_posix==1 and OS!="mac" and OS!="ios"', {
@@ skipping 3159 matching lines @@
     # 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',
   },
 }