Expand player stats and track metadata

Visible changes:
 - Add loadLatency stat
 - Add mimeType to tracks
 - Track state changes (buffering, playing, paused, ended)

Internal changes:
 - Track switchHistory, playTime, bufferingTime in private Stats struct
 - Remove dead timer code

Change-Id: I4566373251b9876b0d4f762a9d77aa50aea8ed00

lib/util/stream_utils.js

@@ -231,6 +231,9 @@ shaka.util.StreamUtils.getVariantTracks =
       if (codecs != '') codecs += ', ';
       codecs += variant.audio.codecs;
     }
+    var mimeType = null;
+    if (variant.video) mimeType = variant.video.mimeType;
+    else if (variant.audio) mimeType = variant.audio.mimeType;
 
     return {
       id: variant.id,
@@ -242,6 +245,7 @@ shaka.util.StreamUtils.getVariantTracks =
       width: variant.video ? variant.video.width : null,
       height: variant.video ? variant.video.height : null,
       frameRate: variant.video ? variant.video.frameRate : undefined,
+      mimeType: mimeType,
       codecs: codecs
     };
   });
@@ -265,6 +269,7 @@ shaka.util.StreamUtils.getTextTracks = function(period, activeStream) {
       type: 'text',
       language: stream.language,
       kind: stream.kind,
+      mimeType: stream.mimeType,
       codecs: stream.codecs || null
     };
   });