media: Allow config change between clear and encrypted streams

media/filters/decrypting_audio_decoder.cc

Index: media/filters/decrypting_audio_decoder.cc
diff --git a/media/filters/decrypting_audio_decoder.cc b/media/filters/decrypting_audio_decoder.cc
index 6ae354c47b3cd9b999a61c329a3169451e7943e0..d2565ccb593294aa950b16f6baf9c9b98caeea52 100644
--- a/media/filters/decrypting_audio_decoder.cc
+++ b/media/filters/decrypting_audio_decoder.cc
@@ -63,23 +63,17 @@ void DecryptingAudioDecoder::Initialize(const AudioDecoderConfig& config,
   init_cb_ = BindToCurrentLoop(init_cb);
   output_cb_ = BindToCurrentLoop(output_cb);
 
-  // TODO(xhwang): We should be able to DCHECK config.IsValidConfig() and
-  // config.is_encrypted().
+  // TODO(xhwang): We should be able to DCHECK config.IsValidConfig().
   if (!config.IsValidConfig()) {
     DLOG(ERROR) << "Invalid audio stream config.";
     base::ResetAndReturn(&init_cb_).Run(false);
     return;
   }
 
-  // DecryptingAudioDecoder only accepts potentially encrypted stream.
-  if (!config.is_encrypted()) {
-    base::ResetAndReturn(&init_cb_).Run(false);
-    return;
-  }
-
   config_ = config;
 
   if (state_ == kUninitialized) {
+    DCHECK(config.is_encrypted());

[Joey Parrish, 2016/12/01 22:28:10]

This is protecting the renderer?  Might be good to have a comment to that
effect, since it appears to be protecting the decoder.

[ddorwin, 2016/12/05 23:53:04]

There should probably be a comment/TODO with the crbug.

[xhwang, 2016/12/16 20:12:28]

joeyparrish: This is an internal contract between DecoderSelector and
DecryptingAudioDecoder. Today we would only choose DAD when the stream is
encrypted.

ddorwin: comment added. This check will probably stay and I don't feel we need a
TODO here.

     DCHECK(cdm_context);
     if (!cdm_context->GetDecryptor()) {
       MEDIA_LOG(DEBUG, media_log_) << GetDisplayName() << ": no decryptor";
@@ -89,7 +83,8 @@ void DecryptingAudioDecoder::Initialize(const AudioDecoderConfig& config,
 
     decryptor_ = cdm_context->GetDecryptor();
   } else {
-    // Reinitialization (i.e. upon a config change)
+    // Reinitialization (i.e. upon a config change, the new config can be

[ddorwin, 2016/12/05 23:53:04]

The new text seems like a separate thought and maybe a new sentence outside the
().

[xhwang, 2016/12/16 20:12:28]

Done.

+    // encrypted or clear).
     decryptor_->DeinitializeDecoder(Decryptor::kAudio);
   }