Enable WPO for the x64 Official 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 1999 matching lines @@
             'incremental_chrome_dll%': 1,
           }],
           # Don't do incremental linking for large modules on 32-bit or when
           # component=static_library as the toolchain fails due to the size of
           # the .ilk files.
           ['MSVS_OS_BITS==32 or component=="static_library"', {
             'msvs_large_module_debug_link_mode%': '1',  # No
           },{
             'msvs_large_module_debug_link_mode%': '2',  # Yes
           }],
-          ['chrome_pgo_phase!= 0', {
+          ['chrome_pgo_phase!=0 or target_arch=="x64"', {
             'full_wpo_on_official%': 1,
           }],
         ],
         'nacl_win64_defines': [
           # This flag is used to minimize dependencies when building
           # Native Client loader for 64-bit Windows.
           'NACL_WIN64',
         ],
         # Need to include allocator target, but exclude tcmalloc files.
         'use_allocator%': 'winheap',
@@ skipping 4295 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',
   },
 }