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

content/browser/devtools/devtools_power_handler.cc

 // 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.
 
 #include "content/browser/devtools/devtools_power_handler.h"
 
 #include "base/bind.h"
 #include "base/values.h"
 #include "content/browser/devtools/devtools_protocol_constants.h"
 #include "content/browser/power_profiler/power_profiler_service.h"
@@ skipping 62 matching lines @@
 scoped_refptr<DevToolsProtocol::Response>
 DevToolsPowerHandler::OnCanProfilePower(
     scoped_refptr<DevToolsProtocol::Command> command) {
   base::DictionaryValue* result = new base::DictionaryValue();
   result->SetBoolean(devtools::kResult,
                      PowerProfilerService::GetInstance()->IsAvailable());
 
   return command->SuccessResponse(result);
 }
 
+void DevToolsPowerHandler::OnClientDetached() {
+  PowerProfilerService::GetInstance()->RemoveObserver(this);
+}
+
 }  // namespace content