Bug 1272468 - Let sniffer support 'mmp4' ftyp brand. r=jya

MozReview-Commit-ID: IKHEILRmhKP

--HG--
extra : rebase_source : 3a3ca37ff000a82879287b2cfc39e1bdc336a93b

toolkit/components/mediasniffer/nsMediaSniffer.cpp

@@ -45,6 +45,7 @@ nsMediaSnifferEntry sFtypEntries[] = {
   PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4P ", AUDIO_MP4),
   PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "qt  ", VIDEO_QUICKTIME),
   PATTERN_ENTRY("\xFF\xFF\xFF", "iso", VIDEO_MP4), // Could be isom or iso2.
+  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "mmp4", VIDEO_MP4),
 };
 
 static bool MatchesBrands(const uint8_t aData[4], nsACString& aSniffedType)