Pass a |media_log| to FFmpegVideoDecoder and roll ffmpeg

media/ffmpeg/ffmpeg_common.h

Index: media/ffmpeg/ffmpeg_common.h
diff --git a/media/ffmpeg/ffmpeg_common.h b/media/ffmpeg/ffmpeg_common.h
index 85328faacb6e1f5dc45d9a3c1ac350883c38a265..be244dba28780653ae9a24c397330bd78366049a 100644
--- a/media/ffmpeg/ffmpeg_common.h
+++ b/media/ffmpeg/ffmpeg_common.h
@@ -6,6 +6,7 @@
 #define MEDIA_FFMPEG_FFMPEG_COMMON_H_
 
 #include <stdint.h>
+#include <string>
 
 // Used for FFmpeg error codes.
 #include <cerrno>
@@ -150,6 +151,9 @@ AVPixelFormat VideoPixelFormatToAVPixelFormat(VideoPixelFormat video_format);
 ColorSpace AVColorSpaceToColorSpace(AVColorSpace color_space,
                                     AVColorRange color_range);
 
+// Converts an AVERROR error number to a description.
+std::string AVErrorToString(int errnum);
+
 // Returns a 32-bit hash for the given codec name.  See the VerifyUmaCodecHashes
 // unit test for more information and code for generating the histogram XML.
 MEDIA_EXPORT int32_t HashCodecName(const char* codec_name);