Move screen_orientation public headers to module directory.

public/platform/modules/screen_orientation/WebLockOrientationError.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
+// Copyright 2015 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 WebLockOrientationError_h
 #define WebLockOrientationError_h
 
 namespace blink {
 
 enum WebLockOrientationError {
     // If locking isn't available on the platform.
     WebLockOrientationErrorNotAvailable,
 
     // If fullscreen is required to lock.
     WebLockOrientationErrorFullScreenRequired,
 
     // If another lock/unlock got called before that one ended.
     WebLockOrientationErrorCanceled,
 };
 
 } // namespace blink
 
 #endif // WebLockOrientationError_h