Introduce PlatformEvent to handle Device events, Battery events and Gamepad events.

Source/core/frame/DeviceEventControllerBase.cpp

Index: Source/core/frame/DeviceEventControllerBase.cpp
diff --git a/Source/core/frame/DeviceEventControllerBase.cpp b/Source/core/frame/DeviceEventControllerBase.cpp
deleted file mode 100644
index d9cbced9539de5c32df99f23e04091bf671ebaf4..0000000000000000000000000000000000000000
--- a/Source/core/frame/DeviceEventControllerBase.cpp
+++ /dev/null
@@ -1,70 +0,0 @@
-// 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 "config.h"
-#include "core/frame/DeviceEventControllerBase.h"
-
-#include "core/page/Page.h"
-
-namespace blink {
-
-DeviceEventControllerBase::DeviceEventControllerBase(Page* page)
-    : PageLifecycleObserver(page)
-    , m_hasEventListener(false)
-    , m_isActive(false)
-    , m_timer(this, &DeviceEventControllerBase::oneShotCallback)
-{
-}
-
-DeviceEventControllerBase::~DeviceEventControllerBase()
-{
-}
-
-void DeviceEventControllerBase::oneShotCallback(Timer<DeviceEventControllerBase>* timer)
-{
-    ASSERT_UNUSED(timer, timer == &m_timer);
-    ASSERT(hasLastData());
-    ASSERT(!m_timer.isActive());
-
-    didUpdateData();
-}
-
-void DeviceEventControllerBase::startUpdating()
-{
-    if (m_isActive)
-        return;
-
-    if (hasLastData() && !m_timer.isActive()) {
-        // Make sure to fire the data as soon as possible.
-        m_timer.startOneShot(0, FROM_HERE);
-    }
-
-    registerWithDispatcher();
-    m_isActive = true;
-}
-
-void DeviceEventControllerBase::stopUpdating()
-{
-    if (!m_isActive)
-        return;
-
-    if (m_timer.isActive())
-        m_timer.stop();
-
-    unregisterWithDispatcher();
-    m_isActive = false;
-}
-
-void DeviceEventControllerBase::pageVisibilityChanged()
-{
-    if (!m_hasEventListener)
-        return;
-
-    if (page()->visibilityState() == PageVisibilityStateVisible)
-        startUpdating();
-    else
-        stopUpdating();
-}
-
-} // namespace blink