Have PlatformEventObserver implementations orderly stop on destruction.

content/renderer/battery_status/battery_status_dispatcher.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 "battery_status_dispatcher.h"
 
 #include "content/common/battery_status_messages.h"
 #include "content/renderer/render_thread_impl.h"
 #include "third_party/WebKit/public/platform/WebBatteryStatusListener.h"
 
 namespace content {
 
 BatteryStatusDispatcher::BatteryStatusDispatcher(RenderThread* thread)
     : PlatformEventObserver<blink::WebBatteryStatusListener>(thread) {
 }
 
 BatteryStatusDispatcher::~BatteryStatusDispatcher() {
+  StopIfObserving();
 }
 
 bool BatteryStatusDispatcher::OnControlMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(BatteryStatusDispatcher, message)
     IPC_MESSAGE_HANDLER(BatteryStatusMsg_DidChange, OnDidChange)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ skipping 11 matching lines @@
     const blink::WebBatteryStatus& status) {
   if (listener())
     listener()->updateBatteryStatus(status);
 }
 
 void BatteryStatusDispatcher::SendFakeDataForTesting(void* fake_data) {
   OnDidChange(*static_cast<blink::WebBatteryStatus*>(fake_data));
 }
 
 }  // namespace content