Coverity fix: Big parameter passed by value

chrome/common/net/gaia/oauth2_access_token_fetcher.cc

 // Copyright (c) 2011 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 "chrome/common/net/gaia/oauth2_access_token_fetcher.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 134 matching lines @@
   std::string access_token;
   ParseGetAccessTokenResponse(source, &access_token);
   OnGetTokenSuccess(access_token);
 }
 
 void OAuth2AccessTokenFetcher::OnGetTokenSuccess(
     const std::string& access_token) {
   consumer_->OnGetTokenSuccess(access_token);
 }
 
-void OAuth2AccessTokenFetcher::OnGetTokenFailure(GoogleServiceAuthError error) {
+void OAuth2AccessTokenFetcher::OnGetTokenFailure(
+    const GoogleServiceAuthError& error) {
   state_ = ERROR_STATE;
   consumer_->OnGetTokenFailure(error);
 }
 
 void OAuth2AccessTokenFetcher::OnURLFetchComplete(const URLFetcher* source) {
   CHECK(source);
   CHECK(state_ == GET_ACCESS_TOKEN_STARTED);
   EndGetAccessToken(source);
 }
 
@@ skipping 39 matching lines @@
   std::string data;
   source->GetResponseAsString(&data);
   base::JSONReader reader;
   scoped_ptr<base::Value> value(reader.Read(data, false));
   if (!value.get() || value->GetType() != base::Value::TYPE_DICTIONARY)
     return false;
 
   DictionaryValue* dict = static_cast<DictionaryValue*>(value.get());
   return GetStringFromDictionary(dict, kAccessTokenKey, access_token);
 }