Enable strict-virtual-specifiers for iOS builds.

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 2118 matching lines @@
         'grit_defines': ['-D', 'enable_service_discovery'],
         'enable_service_discovery%': 1
       }],
       ['clang_use_chrome_plugins==1 and OS!="win"', {
         'clang_chrome_plugins_flags': [
           '<!@(<(DEPTH)/tools/clang/scripts/plugin_flags.sh)'
         ],
         'conditions': [
           # TODO(dcheng): https://crbug.com/417463 -- work to enable this flag
           # on all platforms is currently underway.
-          ['(OS=="linux" and chromeos==0) or OS=="mac"', {
+          ['(OS=="linux" and chromeos==0) or OS=="mac" or OS=="ios"', {
             'clang_chrome_plugins_flags': [
               '-Xclang',
               '-plugin-arg-find-bad-constructs',
               '-Xclang',
               'strict-virtual-specifiers',
             ],
           }],
         ],
       }],
       ['asan==1 or msan==1 or lsan==1 or tsan==1', {
@@ skipping 3691 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',
   },
 }