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

google_apis/google_api_keys.cc

Index: google_apis/google_api_keys.cc
diff --git a/google_apis/google_api_keys.cc b/google_apis/google_api_keys.cc
index 94f6812ab7494f0534857b92a5a6b6fefca4d83e..2cf92fd0bf9ea623ff4f3e4e66c2a2c2dcafa032 100644
--- a/google_apis/google_api_keys.cc
+++ b/google_apis/google_api_keys.cc
@@ -269,4 +269,12 @@ 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