Refactor code listening to platform events in content/renderer/.

content/public/renderer/renderer_gamepad_provider.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_GAMEPAD_RENDERER_PROVIDER_H_
-#define CONTENT_GAMEPAD_RENDERER_PROVIDER_H_
+#ifndef CONTENT_PUBLIC_RENDERER_RENDERER_GAMEPAD_PROVIDER_H_
+#define CONTENT_PUBLIC_RENDERER_RENDERER_GAMEPAD_PROVIDER_H_
+
+#include "content/public/renderer/platform_event_observer.h"
 
 namespace blink {
 class WebGamepadListener;
 class WebGamepads;
 }
 
 namespace content {
 
 // Provides gamepad data and events for blink.
-class RendererGamepadProvider {
+class RendererGamepadProvider
+    : public PlatformEventObserver<blink::WebGamepadListener> {
  public:
+  explicit RendererGamepadProvider(RenderThread* thread)
+      : PlatformEventObserver<blink::WebGamepadListener>(thread) { }
+
+  virtual ~RendererGamepadProvider() {}
+
   // Provides latest snapshot of gamepads.
   virtual void SampleGamepads(blink::WebGamepads& gamepads) = 0;
 
-  // Registers listener for be notified of events.
-  virtual void SetGamepadListener(blink::WebGamepadListener* listener) = 0;
-
  protected:
-  virtual ~RendererGamepadProvider() {}
+  DISALLOW_COPY_AND_ASSIGN(RendererGamepadProvider);
 };
 
 } // namespace content
 
 #endif