GN: fixes for the official build.

build/config/BUILD.gn

Index: build/config/BUILD.gn
diff --git a/build/config/BUILD.gn b/build/config/BUILD.gn
index 2427b72afd920cf6b85a48d83f42a19fe5184bd4..3857648be20765f3d475bbb8147974e204873f26 100644
--- a/build/config/BUILD.gn
+++ b/build/config/BUILD.gn
@@ -41,9 +41,8 @@ declare_args() {
 #
 # For now we define these globally to match the current GYP build.
 config("feature_flags") {
-  # TODO(brettw) most of these need to be parameterized.
+  # TODO(brettw) this probably needs to be parameterized.
   defines = [
-    "CHROMIUM_BUILD",
     "V8_DEPRECATION_WARNINGS",  # Don't use deprecated V8 APIs anywhere.
   ]
 
@@ -239,6 +238,14 @@ config("feature_flags") {
     defines += [ "MOBILE_SAFE_BROWSING" ]
     defines += [ "SAFE_BROWSING_SERVICE" ]
   }
+  if (is_official_build) {
+    defines += [ "OFFICIAL_BUILD" ]
+  }
+  if (is_chrome_branded) {
+    defines += [ "GOOGLE_CHROME_BUILD" ]
+  } else {
+    defines += [ "CHROMIUM_BUILD" ]
+  }
 }
 
 # Debug/release ----------------------------------------------------------------