Isolate check_internal.py to the .gypi files that need it.

build/common.gypi

 # 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 657 matching lines @@
           'use_openmax_dl_fft%': 1,
         }, {
           'use_openmax_dl_fft%': 0,
         }],
       ],
 
       # Set this to 1 to enable use of concatenated impulse responses
       # for the HRTF panner in WebAudio.
       'use_concatenated_impulse_responses': 1,
 
-      # Set this to 1 to use the Google-internal file containing
-      # official API keys for Google Chrome even in a developer build.
-      # Setting this variable explicitly to 1 will cause your build to
-      # fail if the internal file is missing.
+      # You can set the variable 'use_official_google_api_keys' to 1
+      # to use the Google-internal file containing official API keys
+      # for Google Chrome even in a developer build.  Setting this
+      # variable explicitly to 1 will cause your build to fail if the
+      # internal file is missing.
       #
-      # Set this to 0 to not use the internal file, even when it
-      # exists in your checkout.
+      # The variable is documented here, but not handled in this file;
+      # see //google_apis/determine_use_official_keys.gypi for the
+      # implementation.
       #
-      # Leave set to 2 to have this variable implicitly set to 1 if
-      # you have src/google_apis/internal/google_chrome_api_keys.h in
-      # your checkout, and implicitly set to 0 if not.
+      # Set the variable to 0 to not use the internal file, even when
+      # it exists in your checkout.
       #
-      # Note that official builds always behave as if this variable
+      # Leave it unset in your include.gypi to have the variable
+      # implicitly set to 1 if you have
+      # src/google_apis/internal/google_chrome_api_keys.h in your
+      # checkout, and implicitly set to 0 if not.
+      #
+      # Note that official builds always behave as if the variable
       # was explicitly set to 1, i.e. they always use official keys,
       # and will fail to build if the internal file is missing.
-      'use_official_google_api_keys%': 2,
+      #
+      # NOTE: You MUST NOT explicitly set the variable to 2 in your
+      # include.gypi or by other means. Due to subtleties of GYP, this
+      # is not the same as leaving the variable unset, even though its
+      # default value in
+      # //google_apis/determine_use_official_keys.gypi is 2.
 
       # Set these to bake the specified API keys and OAuth client
       # IDs/secrets into your build.
       #
       # If you create a build without values baked in, you can instead
       # set environment variables to provide the keys at runtime (see
       # src/google_apis/google_api_keys.h for details).  Features that
       # require server-side APIs may fail to work if no keys are
       # provided.
       #
@@ skipping 86 matching lines @@
     'sas_dll_path%': '<(sas_dll_path)',
     'wix_path%': '<(wix_path)',
     'use_libjpeg_turbo%': '<(use_libjpeg_turbo)',
     'use_system_libjpeg%': '<(use_system_libjpeg)',
     'android_webview_build%': '<(android_webview_build)',
     'gyp_managed_install%': 0,
     'google_tv%': '<(google_tv)',
     'enable_app_list%': '<(enable_app_list)',
     'use_default_render_theme%': '<(use_default_render_theme)',
     'enable_settings_app%': '<(enable_settings_app)',
-    'use_official_google_api_keys%': '<(use_official_google_api_keys)',
     'google_api_key%': '<(google_api_key)',
     'google_default_client_id%': '<(google_default_client_id)',
     'google_default_client_secret%': '<(google_default_client_secret)',
     'enable_managed_users%': '<(enable_managed_users)',
     'spdy_proxy_auth_origin%': '<(spdy_proxy_auth_origin)',
     'spdy_proxy_auth_property%': '<(spdy_proxy_auth_property)',
 
     # Use system mesa instead of bundled one.
     'use_system_mesa%': 0,
 
@@ skipping 276 matching lines @@
         'directx_sdk_path%': '<(directx_sdk_default_path)',
       }, {
         'directx_sdk_path%': '$(DXSDK_DIR)',
       }],
       ['OS=="win"', {
         'windows_driver_kit_path%': '$(WDK_DIR)',
         # Set the python arch to prevent conflicts with pyauto on Win64 build.
         # TODO(jschuh): crbug.com/177664 Investigate Win64 pyauto build.
         'python_arch%': 'ia32',
       }],
-      # If use_official_google_api_keys is already set (to 0 or 1), we
-      # do none of the implicit checking.  If it is set to 1 and the
-      # internal keys file is missing, the build will fail at compile
-      # time.  If it is set to 0 and keys are not provided by other
-      # means, a warning will be printed at compile time.
-      ['use_official_google_api_keys==2', {
-        'use_official_google_api_keys%':
-            '<!(python <(DEPTH)/google_apis/build/check_internal.py <(DEPTH)/google_apis/internal/google_chrome_api_keys.h)',
-      }],
       ['os_posix==1 and OS!="mac" and OS!="ios"', {
         # Figure out the python architecture to decide if we build pyauto.
         'python_arch%': '<!(<(DEPTH)/build/linux/python_arch.sh <(sysroot)/usr/<(system_libdir)/libpython<(python_ver).so.1.0)',
         'conditions': [
           ['target_arch=="mipsel"', {
             'werror%': '',
             'disable_nacl%': 1,
             'nacl_untrusted_build%': 0,
             'linux_use_tcmalloc%': 0,
             'linux_breakpad%': 0,
@@ skipping 3345 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }