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

Source/core/frame/DeviceSingleWindowEventController.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/DeviceSingleWindowEventController.h"
+
+#include "core/dom/Document.h"
+#include "core/frame/DOMWindow.h"
+#include "core/page/Page.h"
+
+namespace WebCore {
+
+DeviceSingleWindowEventController::DeviceSingleWindowEventController(Document& document)
+    : DeviceEventControllerBase(document.page())
+    , DOMWindowLifecycleObserver(document.domWindow())
+    , m_needsCheckingNullEvents(true)
+    , m_document(document)
+{
+}
+
+DeviceSingleWindowEventController::~DeviceSingleWindowEventController()
+{
+}
+
+void DeviceSingleWindowEventController::didUpdateData()
+{
+    dispatchDeviceEvent(lastEvent());
+}
+
+void DeviceSingleWindowEventController::dispatchDeviceEvent(PassRefPtrWillBeRawPtr<Event> prpEvent)
+{
+    if (!m_document.domWindow() || m_document.activeDOMObjectsAreSuspended() || m_document.activeDOMObjectsAreStopped())
+        return;
+
+    RefPtrWillBeRawPtr<Event> event = prpEvent;
+    m_document.domWindow()->dispatchEvent(event);
+
+    if (m_needsCheckingNullEvents) {
+        if (isNullEvent(event.get()))
+            stopUpdating();
+        else
+            m_needsCheckingNullEvents = false;
+    }
+}
+
+void DeviceSingleWindowEventController::didAddEventListener(DOMWindow* window, const AtomicString& eventType)
+{
+    if (eventType != eventTypeName())
+        return;
+
+    if (page() && page()->visibilityState() == PageVisibilityStateVisible)
+        startUpdating();
+
+    m_hasEventListener = true;
+}
+
+void DeviceSingleWindowEventController::didRemoveEventListener(DOMWindow* window, const AtomicString& eventType)
+{
+    if (eventType != eventTypeName() || window->hasEventListeners(eventTypeName()))
+        return;
+
+    stopUpdating();
+    m_hasEventListener = false;
+}
+
+void DeviceSingleWindowEventController::didRemoveAllEventListeners(DOMWindow*)
+{
+    stopUpdating();
+    m_hasEventListener = false;
+}
+
+} // namespace WebCore