Coverity: Fix pass by value error in GaiaOAuthClient::Core.

chrome/common/net/gaia/gaia_oauth_client.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 "chrome/common/net/gaia/gaia_oauth_client.h"
 
 #include "base/json/json_reader.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
@@ skipping 32 matching lines @@
                     int max_retries,
                     GaiaOAuthClient::Delegate* delegate);
 
   // content::URLFetcherDelegate implementation.
   virtual void OnURLFetchComplete(const net::URLFetcher* source);
 
  private:
   friend class base::RefCountedThreadSafe<Core>;
   virtual ~Core() {}
 
-  void MakeGaiaRequest(std::string post_body,
+  void MakeGaiaRequest(const std::string& post_body,
                        int max_retries,
                        GaiaOAuthClient::Delegate* delegate);
   void HandleResponse(const net::URLFetcher* source,
                       bool* should_retry_request);
 
   GURL gaia_url_;
   int num_retries_;
   scoped_refptr<net::URLRequestContextGetter> request_context_getter_;
   GaiaOAuthClient::Delegate* delegate_;
   scoped_ptr<content::URLFetcher> request_;
@@ skipping 23 matching lines @@
       "refresh_token=" + net::EscapeUrlEncodedData(refresh_token, true) +
       "&client_id=" + net::EscapeUrlEncodedData(oauth_client_info.client_id,
                                                 true) +
       "&client_secret=" +
       net::EscapeUrlEncodedData(oauth_client_info.client_secret, true) +
       "&grant_type=refresh_token";
   MakeGaiaRequest(post_body, max_retries, delegate);
 }
 
 void GaiaOAuthClient::Core::MakeGaiaRequest(
-    std::string post_body,
+    const std::string& post_body,
     int max_retries,
     GaiaOAuthClient::Delegate* delegate) {
   DCHECK(!request_.get()) << "Tried to fetch two things at once!";
   delegate_ = delegate;
   num_retries_ = 0;
   request_.reset(content::URLFetcher::Create(
       0, gaia_url_, content::URLFetcher::POST, this));
   request_->SetRequestContext(request_context_getter_);
   request_->SetUploadData("application/x-www-form-urlencoded", post_body);
   request_->SetMaxRetries(max_retries);
@@ skipping 91 matching lines @@
                                    const std::string& refresh_token,
                                    int max_retries,
                                    Delegate* delegate) {
   return core_->RefreshToken(oauth_client_info,
                              refresh_token,
                              max_retries,
                              delegate);
 }
 
 }  // namespace gaia