Add a function for determining if official Google Chrome API key is used.

google_apis/google_api_keys.cc

 // 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.
 
 #include "google_apis/google_api_keys.h"
 
 // If you add more includes to this list, you also need to add them to
 // google_api_keys_unittest.cc.
 #include "base/command_line.h"
 #include "base/environment.h"
@@ skipping 251 matching lines @@
 }
 
 std::string GetOAuth2ClientID(OAuth2Client client) {
   return g_api_key_cache.Get().GetClientID(client);
 }
 
 std::string GetOAuth2ClientSecret(OAuth2Client client) {
   return g_api_key_cache.Get().GetClientSecret(client);
 }
 
+bool IsGoogleChromeAPIKeyUsed() {
+#if defined(GOOGLE_CHROME_BUILD) || defined(USE_OFFICIAL_GOOGLE_API_KEYS)
+  return true;
+#else
+  return false;
+#endif
+}
+
 }  // namespace google_apis