Use Promises for screen.lockOrientation().

public/platform/WebLockOrientationCallback.h

+// 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.
+
+#ifndef WebLockOrientationCallback_h
+#define WebLockOrientationCallback_h
+
+#include "public/platform/WebScreenOrientationType.h"
+
+namespace blink {
+
+// WebScreenOrientationType is an interface to be used by the embedder in order
+// to inform Blink when a screen lock operation has succeeded or failed.
+// A success notification comes with the new orientation angle and orientation
+// type and a failure notification comes with an information about the type of
+// failure.
+class WebLockOrientationCallback {
+public:
+    enum ErrorType {
+        ErrorTypeNotAvailable, // If locking isn't available on the platform.
+        ErrorTypeFullScreenRequired, // If fullscreen is required to lock.
+        ErrorTypeCanceled, // If another lock/unlock got called before that one ended.
+    };
+
+    virtual ~WebLockOrientationCallback() { }
+
+    virtual void onSuccess(unsigned angle, WebScreenOrientationType) = 0;
+    virtual void onError(ErrorType) = 0;
+};
+
+} // namespace blink
+
+#endif // WebLockOrientationCallback_h