media: Support better decoder switching

media/filters/decoder_selector.h

Index: media/filters/decoder_selector.h
diff --git a/media/filters/decoder_selector.h b/media/filters/decoder_selector.h
index 09378b86c113745a5b9cbb6ba0f7b5235665f426..3431999aaafe83bb2f240a0b6bd8a0475989425d 100644
--- a/media/filters/decoder_selector.h
+++ b/media/filters/decoder_selector.h
@@ -39,6 +39,9 @@ class MEDIA_EXPORT DecoderSelector {
   typedef typename StreamTraits::DecoderType Decoder;
   typedef typename StreamTraits::DecoderConfigType DecoderConfig;
 
+  // Callback to create a list of decoders to select from.
+  using CreateDecodersCB = base::RepeatingCallback<ScopedVector<Decoder>()>;

[sandersd (OOO until July 31), 2017/04/24 20:55:14]

Is now perhaps a good time to replace this ScopedVector?

[xhwang, 2017/04/25 00:43:30]

Agreed, and this is the tracking bug:
https://bugs.chromium.org/p/chromium/issues/detail?id=588249

But I don't think this should be in this CL. Could be done in a follow up CL.

+
   // Indicates completion of Decoder selection.
   // - First parameter: The initialized Decoder. If it's set to NULL, then
   // Decoder initialization failed.
@@ -48,14 +51,13 @@ class MEDIA_EXPORT DecoderSelector {
   // Note: The caller owns selected Decoder and DecryptingDemuxerStream.
   // The caller should call DecryptingDemuxerStream::Reset() before
   // calling Decoder::Reset() to release any pending decryption or read.
-  typedef base::Callback<void(std::unique_ptr<Decoder>,
-                              std::unique_ptr<DecryptingDemuxerStream>)>
-      SelectDecoderCB;
+  using SelectDecoderCB =
+      base::Callback<void(std::unique_ptr<Decoder>,
+                          std::unique_ptr<DecryptingDemuxerStream>)>;
 
-  // |decoders| contains the Decoders to use when initializing.
   DecoderSelector(
-      const scoped_refptr<base::SingleThreadTaskRunner>& message_loop,
-      ScopedVector<Decoder> decoders,
+      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
+      const CreateDecodersCB& create_decoders_cb,
       const scoped_refptr<MediaLog>& media_log);
 
   // Aborts pending Decoder selection and fires |select_decoder_cb| with
@@ -74,6 +76,7 @@ class MEDIA_EXPORT DecoderSelector {
   void SelectDecoder(StreamTraits* traits,
                      DemuxerStream* stream,
                      CdmContext* cdm_context,
+                     const std::string& blacklisted_decoder,
                      const SelectDecoderCB& select_decoder_cb,
                      const typename Decoder::OutputCB& output_cb,
                      const base::Closure& waiting_for_decryption_key_cb);
@@ -90,7 +93,7 @@ class MEDIA_EXPORT DecoderSelector {
   void ReturnNullDecoder();
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  ScopedVector<Decoder> decoders_;
+  CreateDecodersCB create_decoders_cb_;
   scoped_refptr<MediaLog> media_log_;
 
   StreamTraits* traits_;
@@ -100,10 +103,13 @@ class MEDIA_EXPORT DecoderSelector {
   DemuxerStream* input_stream_;
 
   CdmContext* cdm_context_;
+  std::string blacklisted_decoder_;
   SelectDecoderCB select_decoder_cb_;
   typename Decoder::OutputCB output_cb_;
   base::Closure waiting_for_decryption_key_cb_;
 
+  ScopedVector<Decoder> decoders_;
+
   std::unique_ptr<Decoder> decoder_;
   std::unique_ptr<DecryptingDemuxerStream> decrypted_stream_;