Coverity: Pass parameters by reference.

chrome/browser/automation/testing_automation_provider.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/browser/automation/testing_automation_provider.h"
 
 #include <map>
 #include <string>
 #include <vector>
 
@@ skipping 1988 matching lines @@
     snapshot_taker->Start();
   } else {
     LOG(ERROR) << "Could not get render view for tab handle";
     AutomationMsg_CaptureEntirePageAsPNG::WriteReplyParams(reply_message,
                                                            false);
     Send(reply_message);
   }
 }
 
 void TestingAutomationProvider::SendJSONRequest(int handle,
-                                                std::string json_request,
+                                                const std::string& json_request,
                                                 IPC::Message* reply_message) {
   scoped_ptr<Value> values;
   base::JSONReader reader;
   std::string error;
   values.reset(reader.ReadAndReturnError(json_request, true, NULL, &error));
   if (!error.empty()) {
     AutomationJSONReply(this, reply_message).SendError(error);
     return;
   }
 
@@ skipping 3180 matching lines @@
     // If you change this, update Observer for NotificationType::SESSION_END
     // below.
     MessageLoop::current()->PostTask(FROM_HERE,
         NewRunnableMethod(this, &TestingAutomationProvider::OnRemoveProvider));
   }
 }
 
 void TestingAutomationProvider::OnRemoveProvider() {
   AutomationProviderList::GetInstance()->RemoveProvider(this);
 }