GTTF: Add missing virtual destructors.

cc/video_frame_provider.h

 // Copyright (c) 2012 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 CC_VIDEO_FRAME_PROVIDER_H_
 #define CC_VIDEO_FRAME_PROVIDER_H_
 
 #include "base/memory/ref_counted.h"
 
 namespace media {
@@ skipping 17 matching lines @@
     // StopUsingProvider() may be called from any thread. The client should
     // block until it has PutCurrentFrame() any outstanding frames.
     virtual void StopUsingProvider() = 0;
 
     // Notifies the provider's client that a call to GetCurrentFrame() will
     // return new data.
     virtual void DidReceiveFrame() = 0;
 
     // Notifies the provider's client of a new UV transform matrix to be used.
     virtual void DidUpdateMatrix(const float*) = 0;
+
+   protected:
+    virtual ~Client() { }
   };
 
   // May be called from any thread, but there must be some external guarantee
   // that the provider is not destroyed before this call returns.
   virtual void SetVideoFrameProviderClient(Client*) = 0;
 
   // This function places a lock on the current frame and returns a pointer to
   // it. Calls to this method should always be followed with a call to
   // PutCurrentFrame().
   // Only the current provider client should call this function.
   virtual scoped_refptr<media::VideoFrame> GetCurrentFrame() = 0;
 
   // This function releases the lock on the video frame. It should always be
   // called after GetCurrentFrame(). Frames passed into this method
   // should no longer be referenced after the call is made. Only the current
   // provider client should call this function.
   virtual void PutCurrentFrame(const scoped_refptr<media::VideoFrame>&) = 0;
 };
 
 }  // namespace cc
 
 #endif  // CC_VIDEO_FRAME_PROVIDER_H_