Enable full WPO for the PGO builds.

chrome/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/buildflag_header.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/features.gni")
 import("//build/config/locales.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//build/config/win/console_app.gni")
 import("//build/config/win/manifest.gni")
 import("//chrome/chrome_repack_locales.gni")
 import("//chrome/common/features.gni")
 import("//chrome/version.gni")
 import("//ui/base/ui_features.gni")
 
-declare_args() {
-  # Specify the current PGO phase, only used for the Windows MSVS build. Here's
-  # the different values that can be used:
-  #     0 : Means that PGO is turned off.
-  #     1 : Used during the PGI (instrumentation) phase.
-  #     2 : Used during the PGO (optimization) phase.
-  #
-  # TODO(sebmarchand): Add support for the PGU (update) phase.
-  chrome_pgo_phase = 0
-}
-
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 if (is_win) {
   action("reorder_imports") {
     script = "//build/win/reorder-imports.py"
 
     # See comment in chrome_dll.gypi in the hardlink_to_output
     # target for why this cannot be 'initial' like the DLL.
@@ skipping 371 matching lines @@
       ]
 
       if (is_win) {
         if (symbol_level == 2) {
           # Incremental linking doesn't work on this target in debug mode with
           # full symbols, but does work in other cases, including minimal
           # symbols.
           configs -= [ "//build/config/win:default_incremental_linking" ]
           configs += [ "//build/config/win:no_incremental_linking" ]
         }
-        if (chrome_pgo_phase > 0) {
-          cflags += [
-            "/GL",  # Whole program optimization.
-
-            # 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.
-            "/wd4702",
-          ]
-        }
         if (chrome_pgo_phase == 1) {
           ldflags = [
             "/LTCG:PGINSTRUMENT",
             "/PogoSafeMode",
           ]
         } else if (chrome_pgo_phase == 2) {
           ldflags = [ "/LTCG:PGOPTIMIZE" ]
         }
       }
 
@@ skipping 649 matching lines @@
       "//chrome/app/theme/$branding_path_component/product_logo_48.png",
       "//chrome/tools/build/linux/chrome-wrapper",
       "//third_party/xdg-utils/scripts/xdg-mime",
       "//third_party/xdg-utils/scripts/xdg-settings",
     ]
     outputs = [
       "$root_out_dir/{{source_file_part}}",
     ]
   }
 }