Refactors DeviceOrientation to make it more extensible

content/browser/device_orientation/message_filter.cc

+// Copyright (c) 2012 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 "content/browser/device_orientation/message_filter.h"
+
+#include "content/browser/device_orientation/observer_delegate.h"
+#include "content/browser/device_orientation/provider.h"
+#include "content/public/browser/browser_thread.h"
+
+using content::BrowserThread;
+
+namespace device_orientation {
+
+MessageFilter::MessageFilter(DeviceData::Type device_data_type)
+    : provider_(NULL),
+      device_data_type_(device_data_type) {
+}
+
+MessageFilter::~MessageFilter() {
+}
+
+void MessageFilter::OnStartUpdating(int render_view_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  if (!provider_)
+    provider_ = Provider::GetInstance();
+
+  observers_map_[render_view_id] = new ObserverDelegate(device_data_type_,
+      provider_, render_view_id, this);
+}
+
+void MessageFilter::OnStopUpdating(int render_view_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  observers_map_.erase(render_view_id);
+}
+
+}  // namespace device_orientation