Chromium plumbing for Screen Orientation API orientationchange events.

content/renderer/screen_orientation/screen_orientation_dispatcher.cc

+// 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 "content/renderer/screen_orientation/screen_orientation_dispatcher.h"
+
+#include "content/common/screen_orientation_messages.h"
+#include "content/public/renderer/render_thread.h"
+#include "third_party/WebKit/public/platform/WebScreenOrientationListener.h"
+
+namespace content {
+
+ScreenOrientationDispatcher::ScreenOrientationDispatcher(
+    RenderThread* thread)
+  : listener_(NULL) {
+    thread->AddObserver(this);
+}
+
+bool ScreenOrientationDispatcher::OnControlMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+
+  IPC_BEGIN_MESSAGE_MAP(ScreenOrientationDispatcher, message)
+    IPC_MESSAGE_HANDLER(ScreenOrientationMsg_OrientationChange,
+                        OnOrientationChange)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+
+  return handled;
+}
+
+void ScreenOrientationDispatcher::OnOrientationChange(int orientation) {
+  if (!listener_)
+    return;
+
+  // TODO(mlamouri): we might want to have OrientationChangeEvent to pass us
+  // a WebScreenOrientation instead of an int so we can let the backend decide
+  // of the relation between angle and orientation name.
+  blink::WebScreenOrientation web_orientation;
+  switch(orientation) {
+    case 0:
+      web_orientation = blink::WebScreenOrientationPortraitPrimary;
+      break;
+    case 90:
+      web_orientation = blink::WebScreenOrientationLandscapePrimary;
+      break;
+    case 180:
+      web_orientation = blink::WebScreenOrientationPortraitSecondary;
+      break;
+    case -90:
+      web_orientation = blink::WebScreenOrientationLandscapeSecondary;
+      break;
+    default:
+      NOTREACHED();

[Cris Neckar, 2014/02/20 18:47:45]

We prefer that you not handle failures when it comes to IPC. Just return as
something has gone wonky.

[mlamouri (slow - plz ping), 2014/02/20 19:01:12]

Done.

+      web_orientation = blink::WebScreenOrientationPortraitPrimary;
+      break;
+  }
+
+  listener_->didChangeScreenOrientation(web_orientation);
+}
+
+void ScreenOrientationDispatcher::setListener(
+    blink::WebScreenOrientationListener* listener) {
+  listener_ = listener;
+}
+
+}  // namespace content