Refactors DeviceOrientation to make it more extensible

content/browser/device_orientation/observer_delegate.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/observer_delegate.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/device_orientation/device_data.h"
+#include "content/browser/device_orientation/orientation.h"
+
+namespace device_orientation {
+
+ObserverDelegate::ObserverDelegate(DeviceData::Type device_data_type,
+                                   Provider* provider, int render_view_id,
+                                   IPC::Sender* sender)
+    : Observer(device_data_type),
+      provider_(provider),
+      render_view_id_(render_view_id),
+      sender_(sender) {
+  provider_->AddObserver(this);
+}
+
+ObserverDelegate::~ObserverDelegate() {
+  provider_->RemoveObserver(this);
+}
+
+void ObserverDelegate::OnDeviceDataUpdate(
+    const DeviceData* device_data, DeviceData::Type device_data_type) {
+  IPC::Message* message = NULL;
+
+  if (device_data)
+    message = device_data->CreateIPCMessage(render_view_id_);
+  else {
+    scoped_ptr<DeviceData> empty_device_data(EmptyDeviceData(device_data_type));
+    if (empty_device_data.get())
+      message = empty_device_data->CreateIPCMessage(render_view_id_);
+  }
+
+  if (message)
+    sender_->Send(message);
+}
+
+DeviceData* ObserverDelegate::EmptyDeviceData(DeviceData::Type type) {

[hans, 2012/07/18 17:21:02]

maybe we should just DCHECK that type is kTypeOrientation here? It's annoying to
have to have code for the case where this function returns NULL. I think it
should be written so that the caller can assume it doesn't return NULL.

[aousterh, 2012/07/20 11:18:52]

Done.

+  if (type == DeviceData::kTypeOrientation)
+    return new Orientation();
+  return NULL;
+}
+
+}  // namespace device_orientation