[WIP] Add Chromium-side support for the Screen Orientation API

content/browser/screen_orientation/screen_orientation_dispatcher_host.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/browser/screen_orientation/screen_orientation_dispatcher_host.h"
+
+#include "content/common/view_messages.h"
+#include "content/port/browser/screen_orientation_provider.h"
+#include "content/public/browser/content_browser_client.h"
+#include "content/public/common/content_client.h"
+
+namespace content {
+
+ScreenOrientationDispatcherHost::ScreenOrientationDispatcherHost()
+  : orientation_lock_(0) {
+  provider_.reset(
+    GetContentClient()->browser()->OverrideScreenOrientationProvider());
+  if (!provider_.get())
+    provider_.reset(CreateProvider());
+}
+
+ScreenOrientationDispatcherHost::~ScreenOrientationDispatcherHost() {
+}
+
+bool ScreenOrientationDispatcherHost::OnMessageReceived(
+    const IPC::Message& message,
+    bool* message_was_ok) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP_EX(ScreenOrientationDispatcherHost,
+                           message,
+                           *message_was_ok)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_LockScreenOrientation, OnLockOrientation)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_UnlockScreenOrientation,
+                        OnUnlockOrientation)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP_EX()
+  return handled;
+}
+
+void ScreenOrientationDispatcherHost::OnLockOrientation(unsigned char lock,
+    bool* result) {
+  if (!provider_.get())
+    return;
+
+  orientation_lock_ =
+      static_cast<ScreenOrientationProvider::Orientations>(lock);
+
+  assert((orientation_lock_ & ScreenOrientationProvider::OrientationAny) == 0);
+
+  // Is it legal to provide empty lock?
+  assert(orientation_lock_);
+
+  *result = provider_->LockOrientation(orientation_lock_);
+}
+
+void ScreenOrientationDispatcherHost::OnUnlockOrientation() {
+  if (!provider_.get())
+    return;
+
+  provider_->UnlockOrientation();
+  orientation_lock_ = 0;
+}
+
+#if !defined(OS_ANDROID)
+// static
+ScreenOrientationProvider* ScreenOrientationDispatcherHost::CreateProvider() {
+  return NULL;
+}
+#endif
+}  // namespace content