text: // Copyright 2014 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 MEDIA_BASE_DEMUXER_STREAM_PROVIDER_H_
  #define MEDIA_BASE_DEMUXER_STREAM_PROVIDER_H_
  
  #include "base/macros.h"
  #include "media/base/demuxer_stream.h"
  #include "media/base/media_export.h"
  #include "media/base/media_url_params.h"
  #include "url/gurl.h"
  
  namespace media {
  
  // Abstract class that defines how to retrieve "media sources" in DemuxerStream
  // form (for most cases) or URL form (for the MediaPlayerRenderer case).
  //
  // The sub-classes do not stricly provide demuxer streams, but because all
  // sub-classes are for the moment Demuxers, this class has not been renamed to
  // "MediaProvider". This class would be a good candidate for renaming, if
  // ever Pipeline were to support this class directly, instead of the Demuxer
  // interface.
  // TODO(tguilbert): Rename this class. See crbug.com/658062.
  //
  // The derived classes must return a non-null value for the getter method
  // associated with their type, and return a null/empty value for other getters.
  class MEDIA_EXPORT DemuxerStreamProvider {
   public:
    enum Type {
      STREAM,  // Indicates GetStream() should be used
      URL,     // Indicates GetUrl() should be used
    };
  
    DemuxerStreamProvider();
    virtual ~DemuxerStreamProvider();
  
    // For Type::STREAM:
    //   Returns the first stream of the given stream type (which is not allowed
    //   to be DemuxerStream::TEXT), or NULL if that type of stream is not
    //   present.
    //   NOTE: Once a DemuxerStream pointer is returned from GetStream it is
    //   guaranteed to stay valid for as long as the Demuxer/DemuxerStreamProvider
    //   is alive. But make no assumption that once GetStream returned a non-null
    //   pointer for some stream type then all subsequent calls will also return
    //   non-null pointer for the same stream type. In MSE Javascript code can
    //   remove SourceBuffer from a MediaSource at any point and this will make
    //   some previously existing streams inaccessible/unavailable.
    // Other types:
    //   Should not be called.
    virtual DemuxerStream* GetStream(DemuxerStream::Type type) = 0;
  
    // For Type::URL:
    //   Returns the URL parameters of the media to play. Empty URLs are legal,
    //   and should be handled appropriately by the caller.
    // Other types:
    //   Should not be called.
    virtual MediaUrlParams GetMediaUrlParams() const;
  
    virtual DemuxerStreamProvider::Type GetType() const;
  
   private:
    DISALLOW_COPY_AND_ASSIGN(DemuxerStreamProvider);
  };
  
  }  // namespace media
  
  #endif  // MEDIA_BASE_DEMUXER_STREAM_PROVIDER_H_
  