Remove WebPresentationClient and WebPresentationController.

public/platform/WebPresentationController.h

-// 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 WebPresentationController_h
-#define WebPresentationController_h
-
-namespace blink {
-
-// The delegate Blink provides to WebPresentationClient in order to get updates.
-class WebPresentationController {
-public:
-    virtual ~WebPresentationController() { }
-
-    // Called when the presentation screen availability changes.
-    // May not be called if there's no registered listener for the event.
-    virtual void didChangeAvailability(bool available) = 0;
-
-    // Indicates if the frame has listeners to the |availablechange| event.
-    virtual bool isAvailableChangeWatched() const = 0;
-};
-
-} // namespace blink
-
-#endif // WebPresentationController_h