Hook up GN official build and branding.

build/gyp_chromium

 #!/usr/bin/env python
 
 # 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.
 
 # This script is wrapper for Chromium that adds some support for how GYP
 # is invoked by Chromium beyond what can be done in the gclient hooks.
 
 import glob
@@ skipping 97 matching lines @@
   return vars_dict
 
 
 def GetArgsStringForGN(supplemental_files):
   """Returns the args to pass to GN.
   Based on a subset of the GYP variables that have been rewritten a bit."""
 
   vars_dict = GetGypVarsForGN(supplemental_files)
   gn_args = ''
 
-  # Map "component=shared_library" to "is_component_build=true"
-  if "component" in vars_dict and vars_dict["component"] == "shared_library":
-    gn_args += ' is_component_build=true'
+  # These tuples of (key, value, gn_arg_string) use the gn_arg_string for
+  # gn when the key is set to the given value in the GYP arguments.
+  remap_cases = [
+      ('branding', 'Chrome', 'is_chrome_branded=true'),
+      ('buildtype', 'Official', 'is_official_build=true'),
+      ('component', 'shared_library', 'is_component_build=true'),
+  ]
+  for i in remap_cases:
+    if i[0] in vars_dict and vars_dict[i[0]] == i[1]:
+      gn_args += ' ' + i[2]
 
   # These string arguments get passed directly.
-  for v in ['window_sdk_path']:
+  for v in ['windows_sdk_path']:
     if v in vars_dict:
       gn_args += ' ' + v + '="' + EscapeStringForGN(vars_dict[v]) + '"'
 
   # Set the GYP flag so BUILD files know they're being invoked in GYP mode.
   gn_args += ' is_gyp=true'
   return gn_args.strip()
 
 
 def additional_include_files(supplemental_files, args=[]):
   """
@@ skipping 171 matching lines @@
   # to enfore syntax checking.
   syntax_check = os.environ.get('CHROMIUM_GYP_SYNTAX_CHECK')
   if syntax_check and int(syntax_check):
     args.append('--check')
 
   print 'Updating projects from gyp files...'
   sys.stdout.flush()
 
   # Off we go...
   sys.exit(gyp.main(args))