Enable /GL for all targets in Official (behind a flag)

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 1362 matching lines @@
     # to get incremental linking to be faster in debug builds.
     'incremental_chrome_dll%': '0',
 
     # Experimental setting to break chrome.dll into multiple pieces based on
     # process type.
     'chrome_multiple_dll%': '0',
 
     # Experimental setting to optimize Chrome's DLLs with PGO.
     'chrome_pgo_phase%': '0',
 
+    # Experimental setting to build the official builds with full WPO.
+    'full_wpo_on_official%': '0',
+
     # Whether the VS xtree header has been patched to disable warning 4702. If
     # it has, then we don't need to disable 4702 (unreachable code warning).
     # The patch is preapplied to the internal toolchain and hence all bots.
     'msvs_xtree_patched%': '<!pymod_do_main(win_is_xtree_patched)',
 
     # Clang stuff.
     'clang%': '<(clang)',
     'host_clang%': '<(host_clang)',
     'make_clang_dir%': '<(make_clang_dir)',
     'use_lld%': '<(use_lld)',
@@ skipping 4100 matching lines @@
               },
             },
             'target_conditions': [
               ['optimize=="size"', {
                 'msvs_settings': {
                   'VCCLCompilerTool': {
                     # 1, optimizeMinSpace, Minimize Size (/O1)
                     'Optimization': '1',
                     # 2, favorSize - Favor small code (/Os)
                     'FavorSizeOrSpeed': '2',
+                    'conditions': [
+                      ['full_wpo_on_official==1', {
+                        # This implies link time code generation.
+                        'WholeProgramOptimization': 'true',
+                      }],
+                    ],
                   },
                 },
               }],
               # This config is used to avoid a problem in ffmpeg, see
               # http://crbug.com/264459.
               ['optimize=="size_no_ltcg"', {
                 'msvs_settings': {
                   'VCCLCompilerTool': {
                     # 1, optimizeMinSpace, Minimize Size (/O1)
                     'Optimization': '1',
                     # 2, favorSize - Favor small code (/Os)
                     'FavorSizeOrSpeed': '2',
                   },
                 },
               }],
               ['optimize=="speed"', {
                 'msvs_settings': {
                   'VCCLCompilerTool': {
                     # 2, optimizeMaxSpeed, Maximize Speed (/O2)
                     'Optimization': '2',
                     # 1, favorSpeed - Favor fast code (/Ot)
                     'FavorSizeOrSpeed': '1',
+                    'conditions': [
+                      ['full_wpo_on_official==1', {
+                        # This implies link time code generation.
+                        'WholeProgramOptimization': 'true',
+                      }],
+                    ],
                   },
                 },
               }],
               ['optimize=="max"', {
                 # Disable Warning 4702 ("Unreachable code") for the WPO/PGO
                 # builds. Probably anything that this would catch that
                 # wouldn't be caught in a normal build isn't going to
                 # actually be a bug, so the incremental value of C4702 for
                 # PGO builds is likely very small.
                 'msvs_disabled_warnings': [
@@ skipping 772 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',
   },
 }