Fix buffer detection in native HLS

Use a fudge factor to fix infinite buffering at the end of a native
HLS playback.  This could go away once we stop managing buffering
state above the browser using playbackRate=0.

Issue #997

Change-Id: Ib4a6fd5aa10dd84f9cfa4972d57db2cc63d7668d

lib/media/play_rate_controller.js

@@ -26,6 +26,8 @@ goog.require('shaka.util.Timer');
  * the playback rate on the media element can change outside of the controller,
  * the playback controller will need to be updated to stay in-sync.
  *
+ * TODO: Try not to manage buffering above the browser with playbackRate=0.
+ *
  * @implements {shaka.util.IReleasable}
  * @final
  */

lib/player.js

@@ -128,6 +128,7 @@ shaka.Player = function(mediaElement, dependencyInjector) {
   // been loaded and are not re-used between loads.
   /** @private {shaka.util.Timer} */
   this.bufferPoller_ = null;
+
   /** @private {shaka.media.BufferingObserver} */
   this.bufferObserver_ = null;
 
@@ -4831,7 +4832,14 @@ shaka.Player.prototype.isBufferedToEndSrc_ = function() {
   // If we have buffered to the duration of the content, it means we will have
   // enough content to buffer to the end of the presentation.
   const bufferEnd = shaka.media.TimeRangesUtils.bufferEnd(this.video_.buffered);
-  return bufferEnd >= this.video_.duration;
+
+  // Because Safari's native HLS reports slightly inaccurate values for
+  // bufferEnd here, we use a fudge factor.  Without this, we can end up in a
+  // buffering state at the end of the stream.
+  // TODO: Try to remove the fudge here once we no longer manage buffering state
+  // above the browser with playbackRate=0.
+  const fudge = 0.05;  // 50 ms
+  return bufferEnd >= this.video_.duration - fudge;
 };