Fix channel layout reporting for implicit signalling of AAC parametric stereo

media/mp4/aac.h

Index: media/mp4/aac.h
diff --git a/media/mp4/aac.h b/media/mp4/aac.h
index e12b6a4d9ff4ef91ad8b0309258eddf43df47366..2d4b6f45416d243ee853b169651e129b0a361611 100644
--- a/media/mp4/aac.h
+++ b/media/mp4/aac.h
@@ -38,7 +38,13 @@ class MEDIA_EXPORT AAC {
   // Returns the samples_per_second value that should used in an
   // AudioDecoderConfig.
   int GetOutputSamplesPerSecond(bool sbr_in_mimetype) const;
-  ChannelLayout channel_layout() const;
+
+  // Gets the channel layout for the AAC stream.
+  // |sbr_in_mimetype| should be set to true if the SBR mode is
+  // signalled in the mimetype. (ie mp4a.40.5 in the codecs parameter).
+  // Returns the channel_layout value that should used in an
+  // AudioDecoderConfig.
+  ChannelLayout GetChannelLayout(bool sbr_in_mimetype) const;
 
   // This function converts a raw AAC frame into an AAC frame with an ADTS
   // header. On success, the function returns true and stores the converted data