Decouple GamepadSharedMemory into Blink.

third_party/WebKit/Source/modules/gamepad/GamepadDispatcher.cpp

 // 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 "modules/gamepad/GamepadDispatcher.h"
 
+#include "modules/gamepad/GamepadSharedMemoryReader.h"

[ke.he, 2016/12/15 14:11:01]

Actually the GamepadSharedMemory can be merged into GamepadDispatcher. I didn't
start that step though.

 #include "modules/gamepad/NavigatorGamepad.h"
 #include "public/platform/Platform.h"
 
 namespace blink {
 
 GamepadDispatcher& GamepadDispatcher::instance() {
   DEFINE_STATIC_LOCAL(GamepadDispatcher, gamepadDispatcher,
                       (new GamepadDispatcher));
   return gamepadDispatcher;
 }
@@ skipping 26 matching lines @@
     bool connected) {
   ASSERT(index < WebGamepads::itemsLengthCap);
   ASSERT(connected == gamepad.connected);
 
   m_latestChange.pad = gamepad;
   m_latestChange.index = index;
   notifyControllers();
 }
 
 void GamepadDispatcher::startListening() {
-  Platform::current()->startListening(WebPlatformEventTypeGamepad, this);
+  if (!m_reader.get()) {
+    m_reader.reset(new GamepadSharedMemoryReader(
+        Platform::current()->interfaceProvider()));
+  }
+  m_reader->start(this);
 }
 
 void GamepadDispatcher::stopListening() {
-  Platform::current()->stopListening(WebPlatformEventTypeGamepad);
+  if (m_reader) {
+    m_reader->stop();
+  }
 }
 
 }  // namespace blink