Enable full WPO for the PGO builds.

chrome/BUILD.gn

Index: chrome/BUILD.gn
diff --git a/chrome/BUILD.gn b/chrome/BUILD.gn
index 00134166531e0c70778268bf80a83a556eba4a08..935017f5d6633e4b94e45b5a5394ffe595f685cc 100644
--- a/chrome/BUILD.gn
+++ b/chrome/BUILD.gn
@@ -16,17 +16,6 @@ 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")
 }
@@ -418,17 +407,6 @@ if (is_mac || is_win) {
           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",