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

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 3ee4412ed255fbde3e0b94f81b767bd353851eac..ce59309b81eb68d94aa1c26d40fdd0cd41fdab58 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -1233,12 +1233,9 @@ if (is_win) {
 # Default "optimization on" config.
 config("optimize") {
   if (is_win) {
-    # TODO(sebmarchand): Enable this once we've decided to ship with full WPO
-    # and when the change to the incompatible projects (FFmpeg and Yasm) have
-    # have been committed.
-    #if (is_official_build) {
-    #  common_optimize_on_cflags += [ "/GL" ]
-    #}
+    if (is_official_build && full_wpo_on_official) {
+      common_optimize_on_cflags += [ "/GL" ]
+    }
 
     # Favor size over speed, /O1 must be before the common flags. The GYP
     # build also specifies /Os and /GF but these are implied by /O1.