Move Preload enum to BufferedDataSource.

content/renderer/media/preload.h

-// Copyright 2013 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 CONTENT_RENDERER_MEDIA_PRELOAD_H_
-#define CONTENT_RENDERER_MEDIA_PRELOAD_H_
-
-namespace content {
-
-// Used to specify video preload states. They are "hints" to the browser about
-// how aggressively the browser should load and buffer data.
-// Please see the HTML5 spec for the descriptions of these values:
-// http://www.w3.org/TR/html5/video.html#attr-media-preload
-//
-// Enum values must match the values in WebCore::MediaPlayer::Preload and
-// there will be assertions at compile time if they do not match.
-enum Preload {
-  NONE,
-  METADATA,
-  AUTO,
-};
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_MEDIA_PRELOAD_H_