Bug 918135 - More tests for MP3FrameParser r=cpearce

This patch introduces two more MP3 test cases to exercise MP3FrameParser:
* vbr-head.mp3: This file contains a Xing header which gives an exact duration
    of 10 seconds. However, it only contains 4 MP3 frames total for a real
    duration of around 1 second. It is expected that we read the Xing header
    and report 10 seconds.
* huge-id3.mp3: This file contains more than 130KB of ID3 tags. When we search
    for MP3 frames, we give up after X KB of non-MP3 data. ID3 tags should not
    count towards the non-MP3 count, since they can be very large. This test
    case makes sure the skipping of ID3 tags works correctly.

content/media/test/manifest.js

@@ -188,6 +188,16 @@ var gPlayTests = [
   // owl.mp3 as above, but with something even funnier going on in the ID3v2 tag
   // that causes DirectShow to fail.
   { name:"owl-funnier-id3.mp3", type:"audio/mpeg", duration:3.29 },
+  // One second of silence with ~140KB of ID3 tags. Usually when the first MP3
+  // frame is at such a high offset into the file, MP3FrameParser will give up
+  // and report that the stream is not MP3. However, it does not count ID3 tags
+  // in that offset. This test case makes sure that ID3 exclusion holds.
+  { name:"huge-id3.mp3", type:"audio/mpeg", duration:1.00 },
+  // A truncated VBR MP3 with just enough frames to keep most decoders happy.
+  // The Xing header reports the length of the file to be around 10 seconds, but
+  // there is really only one second worth of data. We want MP3FrameParser to
+  // trust the header, so this should be reported as 10 seconds.
+  { name:"vbr-head.mp3", type:"audio/mpeg", duration:10.00 },
 
   // Invalid file
   { name:"bogus.duh", type:"bogus/duh", duration:Number.NaN }

content/media/test/mochitest.ini

@@ -97,6 +97,7 @@ support-files =
   fragment_noplay.js
   fragment_play.js
   gizmo.mp4
+  huge-id3.mp3
   id3tags.mp3
   invalid-cmap-s0c0.opus
   invalid-cmap-s0c2.opus
@@ -164,6 +165,7 @@ support-files =
   variable-preskip.opus
   variable-samplerate.ogg
   variable-samplerate.opus
+  vbr-head.mp3
   vbr.mp3
   VID_0001.ogg
   video-overhang.ogg