Support for parsing encrypted WebM streams by src.

media/ffmpeg/ffmpeg_common.cc

Index: media/ffmpeg/ffmpeg_common.cc
diff --git a/media/ffmpeg/ffmpeg_common.cc b/media/ffmpeg/ffmpeg_common.cc
index bf234304aa2b26fb7e0f729a4e75257099c00358..e8a44c7837b444319be7a694cb81ddb75621dcae 100644
--- a/media/ffmpeg/ffmpeg_common.cc
+++ b/media/ffmpeg/ffmpeg_common.cc
@@ -295,8 +295,9 @@ static ChannelLayout GuessChannelLayout(int channels) {
   return CHANNEL_LAYOUT_UNSUPPORTED;
 }
 
-void AVCodecContextToAudioDecoderConfig(
+static void AVCodecContextToAudioDecoderConfig(
     const AVCodecContext* codec_context,
+    bool is_encrypted,
     AudioDecoderConfig* config) {
   DCHECK_EQ(codec_context->codec_type, AVMEDIA_TYPE_AUDIO);
 
@@ -320,7 +321,7 @@ void AVCodecContextToAudioDecoderConfig(
                      codec_context->sample_rate,
                      codec_context->extradata,
                      codec_context->extradata_size,
-                     false,  // Not encrypted.
+                     is_encrypted,
                      true);
   if (codec != kCodecOpus) {
     DCHECK_EQ(av_get_bytes_per_sample(codec_context->sample_fmt) * 8,
@@ -328,6 +329,17 @@ void AVCodecContextToAudioDecoderConfig(
   }
 }
 
+void AVStreamToAudioDecoderConfig(
+    const AVStream* stream,
+    AudioDecoderConfig* config) {
+  bool is_encrypted = false;
+  AVDictionaryEntry* key = av_dict_get(stream->metadata, "enc_key_id", NULL, 0);
+  if (key)
+    is_encrypted = true;
+  return AVCodecContextToAudioDecoderConfig(stream->codec,
+                                            is_encrypted, config);
+}
+
 void AudioDecoderConfigToAVCodecContext(const AudioDecoderConfig& config,
                                         AVCodecContext* codec_context) {
   codec_context->codec_type = AVMEDIA_TYPE_AUDIO;
@@ -391,12 +403,17 @@ void AVStreamToVideoDecoderConfig(
     coded_size = natural_size;
   }
 
+  bool is_encrypted = false;
+  AVDictionaryEntry* key = av_dict_get(stream->metadata, "enc_key_id", NULL, 0);
+  if (key)
+    is_encrypted = true;
+
   config->Initialize(codec,
                      profile,
                      format,
                      coded_size, visible_rect, natural_size,
                      stream->codec->extradata, stream->codec->extradata_size,
-                     false,  // Not encrypted.
+                     is_encrypted,
                      true);
 }