[DevTools] Add implementation for Tracing.start with optional parameters.

content/browser/devtools/protocol/tracing_handler.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_BROWSER_DEVTOOLS_PROTOCOL_TRACING_HANDLER_H_
 #define CONTENT_BROWSER_DEVTOOLS_PROTOCOL_TRACING_HANDLER_H_
 
 #include "content/browser/devtools/protocol/devtools_protocol_handler_impl.h"
 
 namespace content {
 namespace devtools {
 namespace tracing {
 
 class TracingHandler {
  public:
   typedef DevToolsProtocolClient::Response Response;
 
   TracingHandler();
   virtual ~TracingHandler();
 
   void SetClient(scoped_ptr<Client> client);
 
-  // TODO(dgozman): remove sync version after migration.
-  Response Start(const std::string& categories,
-                 const std::string& options,
-                 const double* buffer_usage_reporting_interval);
   scoped_refptr<DevToolsProtocol::Response> Start(
       const std::string& categories,
       const std::string& options,
       const double* buffer_usage_reporting_interval,
       scoped_refptr<DevToolsProtocol::Command> command);
+  scoped_refptr<DevToolsProtocol::Response> Start(
+      const std::string* categories,
+      const std::string* options,
+      const double* buffer_usage_reporting_interval,
+      scoped_refptr<DevToolsProtocol::Command> command);
 
-  // TODO(dgozman): remove sync version after migration.
-  Response End();
   scoped_refptr<DevToolsProtocol::Response> End(
       scoped_refptr<DevToolsProtocol::Command> command);
 
   scoped_refptr<DevToolsProtocol::Response> GetCategories(
       scoped_refptr<DevToolsProtocol::Command> command);
 
  private:
   scoped_ptr<Client> client_;
 
   DISALLOW_COPY_AND_ASSIGN(TracingHandler);
 };
 
 }  // namespace tracing
 }  // namespace devtools
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_PROTOCOL_TRACING_HANDLER_H_