[PowerProfiler] Power profiler service keeps running even after devtools frontend has been closed.

content/browser/devtools/devtools_power_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_DEVTOOLS_POWER_HANDLER_H_
 #define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_POWER_HANDLER_H_
 
 #include "base/time/time.h"
 #include "content/browser/devtools/devtools_protocol.h"
 #include "content/browser/power_profiler/power_profiler_observer.h"
 
 namespace content {
 
+class DevToolsAgentHost;
+
 // This class provides power information to DevTools.
 class DevToolsPowerHandler
     : public DevToolsProtocol::Handler,
       public PowerProfilerObserver {
  public:
-  DevToolsPowerHandler();
+  DevToolsPowerHandler(DevToolsAgentHost*);

[yurys, 2014/06/18 15:20:59]

should be explicit

   virtual ~DevToolsPowerHandler();
 
   // PowerProfilerObserver override.
   virtual void OnPowerEvent(const PowerEventVector&) OVERRIDE;
 
  private:
   scoped_refptr<DevToolsProtocol::Response> OnStart(
       scoped_refptr<DevToolsProtocol::Command> command);
   scoped_refptr<DevToolsProtocol::Response> OnEnd(
       scoped_refptr<DevToolsProtocol::Command> command);
   scoped_refptr<DevToolsProtocol::Response> OnCanProfilePower(
       scoped_refptr<DevToolsProtocol::Command> command);
+  void OnDevToolsStateChanged(content::DevToolsAgentHost* agent_host,
+                              bool attached);
+
+  DevToolsAgentHost* devtools_agent_host_;
+  base::Callback<void(content::DevToolsAgentHost*, bool)> devtools_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsPowerHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_POWER_HANDLER_H_