Load CMA backend from shared library

chromecast/media/base/media_codec_support.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 CHROMECAST_MEDIA_BASE_MEDIA_CODEC_SUPPORT_H_
 #define CHROMECAST_MEDIA_BASE_MEDIA_CODEC_SUPPORT_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "net/base/mime_util.h"
 
 // TODO(gunsch/servolk): remove when this definition exists upstream.
-
 namespace net {
 typedef base::Callback<bool(const std::string&)> IsCodecSupportedCB;
-bool DefaultIsCodecSupported(const std::string&);
 }
 
 namespace chromecast {
 namespace media {
 
-// This function should return a callback capable of deciding whether a given
-// codec (passed in as a string representation of the codec id conforming to
-// RFC 6381) is supported or not. The implementation of this function is
-// expected to be provided somewhere in the vendor platform-specific libraries
-// that will get linked with cast_shell_common target.
+// Returns the callback to decide whether a given codec (passed in as a string
+// representation of the codec id conforming to RFC 6381) is supported or not.
 net::IsCodecSupportedCB GetIsCodecSupportedOnChromecastCB();
 
 }  // namespace media
 }  // namespace chromecast
 
 #endif  // CHROMECAST_MEDIA_BASE_MEDIA_CODEC_SUPPORT_H_
-