Log MediaSource parsing errors to the MediaLog so they can appear in chrome:media-internals.

media/filters/source_buffer_stream.h

Index: media/filters/source_buffer_stream.h
diff --git a/media/filters/source_buffer_stream.h b/media/filters/source_buffer_stream.h
index a3757cbaa1c021fd94499d393354b4907e0b33a4..32de33329f20b10adeae08965be97b98fe7b3360 100644
--- a/media/filters/source_buffer_stream.h
+++ b/media/filters/source_buffer_stream.h
@@ -18,6 +18,7 @@
 #include "base/memory/ref_counted.h"
 #include "media/base/audio_decoder_config.h"
 #include "media/base/media_export.h"
+#include "media/base/media_log.h"
 #include "media/base/ranges.h"
 #include "media/base/stream_parser_buffer.h"
 #include "media/base/video_decoder_config.h"
@@ -42,8 +43,10 @@ class MEDIA_EXPORT SourceBufferStream {
     kConfigChange,
   };
 
-  explicit SourceBufferStream(const AudioDecoderConfig& audio_config);
-  explicit SourceBufferStream(const VideoDecoderConfig& video_config);
+  SourceBufferStream(const AudioDecoderConfig& audio_config,
+                     const LogCB& log_cb);
+  SourceBufferStream(const VideoDecoderConfig& video_config,
+                     const LogCB& log_cb);
 
   ~SourceBufferStream();
 
@@ -237,6 +240,10 @@ class MEDIA_EXPORT SourceBufferStream {
   // kSuccess.
   void CompleteConfigChange();
 
+  // Callback used to report error strings that can help the web developer
+  // figure out what is wrong with the content.
+  LogCB log_cb_;
+
   // List of disjoint buffered ranges, ordered by start time.
   RangeList ranges_;