Revert r267126: "DevTools: handle Tracing.start in both browser and renderer" It was plain wrong.

content/browser/devtools/devtools_tracing_handler.h

 // 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.
 
 #ifndef CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_TRACING_HANDLER_H_
 #define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_TRACING_HANDLER_H_
 
 #include "base/memory/weak_ptr.h"
 #include "content/browser/devtools/devtools_protocol.h"
 #include "content/public/browser/tracing_controller.h"
 
 namespace base {
 class RefCountedString;
 class Timer;
 }
 
 namespace content {
 
 // This class bridges DevTools remote debugging server with the trace
 // infrastructure.
 class DevToolsTracingHandler : public DevToolsProtocol::Handler {
  public:
   DevToolsTracingHandler();
   virtual ~DevToolsTracingHandler();
 
  private:
   void BeginReadingRecordingResult(const base::FilePath& path);
   void ReadRecordingResult(const scoped_refptr<base::RefCountedString>& result);
   void OnTraceDataCollected(const std::string& trace_fragment);
+  void OnTracingStarted(scoped_refptr<DevToolsProtocol::Command> command);
   void OnBufferUsage(float usage);
 
   scoped_refptr<DevToolsProtocol::Response> OnStart(
       scoped_refptr<DevToolsProtocol::Command> command);
   scoped_refptr<DevToolsProtocol::Response> OnEnd(
       scoped_refptr<DevToolsProtocol::Command> command);
 
   TracingController::Options TraceOptionsFromString(const std::string& options);
 
   base::WeakPtrFactory<DevToolsTracingHandler> weak_factory_;
   scoped_ptr<base::Timer> buffer_usage_poll_timer_;
   DISALLOW_COPY_AND_ASSIGN(DevToolsTracingHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_TRACING_HANDLER_H_