Adds histograms for casting feature of Video Player

ui/file_manager/video_player/js/video_player.js

Index: ui/file_manager/video_player/js/video_player.js
diff --git a/ui/file_manager/video_player/js/video_player.js b/ui/file_manager/video_player/js/video_player.js
index 1c6e04abed05409ce0631908acdbfb6fd65c431b..2c7c80f5e956144f5d07443c4449c8448d018329 100644
--- a/ui/file_manager/video_player/js/video_player.js
+++ b/ui/file_manager/video_player/js/video_player.js
@@ -318,6 +318,8 @@ VideoPlayer.prototype.loadVideo_ = function(video, opt_callback) {
 
     var videoElementInitializePromise;
     if (this.currentCast_) {
+      metrics.recordUserAction('CastVideo');

[Ilya Sherman, 2014/12/02 23:45:10]

This looks like you're recording a user action rather than a histogram.  I'd
recommend recording your set of user actions within one or more enumerated
histograms; but if you prefer user actions, then you'll need to add these to the
actions.xml file rather than the histograms.xml one.

[yoshiki, 2014/12/08 02:52:29]

Thanks for guidance. I've changed it to recording the type of play (local play
or cast). I think it is metrics rather than user action.

+
       videoPlayerElement.setAttribute('casting', true);
 
       document.querySelector('#cast-name').textContent =
@@ -390,6 +392,9 @@ VideoPlayer.prototype.loadVideo_ = function(video, opt_callback) {
         }.bind(this))
         // In case of error.
         .catch(function(error) {
+          if (this.currentCast_)
+            metrics.recordUserAction('CastVideoError');
+
           videoPlayerElement.removeAttribute('loading');
           console.error('Failed to initialize the video element.',
                         error.stack || error);
@@ -668,6 +673,10 @@ var initPromise = Promise.all(
 
 initPromise.then(function(results) {
   var videos = results[0];
+
+  metrics.recordUserAction('OpenVideoPlayer');
+  metrics.recordSmallCount('NumberOfOpenedFiles', videos.length);
+
   player.prepare(videos);
   return new Promise(player.playFirstVideo.wrap(player));
 }.wrap(null));