GTTF: Add missing virtual destructors.

media/filters/ffmpeg_glue.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.
 
 // FFmpegGlue is an interface between FFmpeg and Chrome used to proxy FFmpeg's
 // read and seek requests to Chrome's internal data structures.  The glue works
 // through the AVIO interface provided by FFmpeg.
 //
 // AVIO works through a special AVIOContext created through avio_alloc_context()
 // which is attached to the AVFormatContext used for demuxing.  The AVIO context
@@ skipping 37 matching lines @@
 
   // Returns true if the file position could be set, false otherwise.
   virtual bool SetPosition(int64 position) = 0;
 
   // Returns true and the file size, false if the file size could not be
   // retrieved.
   virtual bool GetSize(int64* size_out) = 0;
 
   // Returns false if this protocol supports random seeking.
   virtual bool IsStreaming() = 0;
+
+ protected:
+  virtual ~FFmpegURLProtocol() { }
 };
 
 class MEDIA_EXPORT FFmpegGlue {
  public:
   static void InitializeFFmpeg();
 
   // See file documentation for usage.  |protocol| must outlive FFmpegGlue.
   explicit FFmpegGlue(FFmpegURLProtocol* protocol);
   ~FFmpegGlue();
 
   // Opens an AVFormatContext specially prepared to process reads and seeks
   // through the FFmpegURLProtocol provided during construction.
   bool OpenContext();
   AVFormatContext* format_context() { return format_context_; }
 
  private:
   bool open_called_;
   AVFormatContext* format_context_;
   scoped_ptr_malloc<AVIOContext, ScopedPtrAVFree> avio_context_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegGlue);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_GLUE_H_