Revert of Generalize and refactor DeviceSensorEvent* architecture to support multi-event type targets.

Source/core/frame/DeviceEventDispatcherBase.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 "config.h"
-#include "core/frame/DeviceEventDispatcherBase.h"
-
-#include "core/frame/DeviceEventControllerBase.h"
-#include "wtf/TemporaryChange.h"
-
-namespace WebCore {
-
-DeviceEventDispatcherBase::DeviceEventDispatcherBase()
-    : m_needsPurge(false)
-    , m_isDispatching(false)
-{
-}
-
-DeviceEventDispatcherBase::~DeviceEventDispatcherBase()
-{
-}
-
-void DeviceEventDispatcherBase::addController(DeviceEventControllerBase* controller)
-{
-    bool wasEmpty = m_controllers.isEmpty();
-    if (!m_controllers.contains(controller))
-        m_controllers.append(controller);
-    if (wasEmpty)
-        startListening();
-}
-
-void DeviceEventDispatcherBase::removeController(DeviceEventControllerBase* controller)
-{
-    // Do not actually remove the controller from the vector, instead zero them out.
-    // The zeros are removed in these two cases:
-    // 1. either immediately if we are not dispatching any events,
-    // 2. or after events to all controllers have dispatched (see notifyControllers()).
-    // This is to correctly handle the re-entrancy case when a controller is destroyed
-    // while the events are still being dispatched.
-    size_t index = m_controllers.find(controller);
-    if (index == kNotFound)
-        return;
-
-    m_controllers[index] = 0;
-    m_needsPurge = true;
-
-    if (!m_isDispatching)
-        purgeControllers();
-}
-
-void DeviceEventDispatcherBase::purgeControllers()
-{
-    ASSERT(m_needsPurge);
-
-    size_t i = 0;
-    while (i < m_controllers.size()) {
-        if (!m_controllers[i]) {
-            m_controllers[i] = m_controllers.last();
-            m_controllers.removeLast();
-        } else {
-            ++i;
-        }
-    }
-
-    m_needsPurge = false;
-
-    if (m_controllers.isEmpty())
-        stopListening();
-}
-
-void DeviceEventDispatcherBase::notifyControllers()
-{
-    {
-        TemporaryChange<bool> changeIsDispatching(m_isDispatching, true);
-        // Don't notify controllers removed or added during event dispatch.
-        size_t size = m_controllers.size();
-        for (size_t i = 0; i < size; ++i) {
-            if (m_controllers[i])
-                m_controllers[i]->didUpdateData();
-        }
-    }
-
-    if (m_needsPurge)
-        purgeControllers();
-}
-
-} // namespace WebCore