clang/win: Turn off Winconsistent-missing-override for now.

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 5555 matching lines @@
                   '-Wno-sometimes-uninitialized',
                   '-Wno-switch',
                   '-Wno-tautological-compare',
                   '-Wno-unknown-pragmas',
                   '-Wno-unsequenced',
                   '-Wno-unused-function',
                   '-Wno-unused-private-field',
                   '-Wno-unused-value',
                   '-Wno-unused-variable',
                   '-Wno-unused-local-typedef',  # http://crbug.com/411648
+                  '-Wno-inconsistent-missing-override', #http://crbug.com/428099
                 ],
               },
             }],
             ['asan==1', {
               # ASan on Windows is a work in progress and very experimental.
               # See crbug.com/345874.
               'VCCLCompilerTool': {
                 'AdditionalOptions': [
                   '-fsanitize=address',
                 ],
@@ skipping 294 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',
   },
 }