[cros] OOBE: add histograms for Profile image fetching.

chrome/browser/resources/chromeos/login/oobe_screen_user_image.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview Oobe user image screen implementation.
  */
 
 cr.define('oobe', function() {
 
@@ skipping 193 matching lines @@
         this.acceptImage_();
     },
 
     /**
      * Event handler that is invoked just before the screen is shown.
      * @param {object} data Screen init payload.
      */
     onBeforeShow: function(data) {
       Oobe.getInstance().headerHidden = true;
       $('user-image-grid').updateAndFocus();
+      chrome.send('onUserImageScreenShown');
     },
 
     /**
      * Accepts currently selected image, if possible.
      * @private
      */
     acceptImage_: function() {
       if (!$('ok-button').disabled)
         chrome.send('onUserImageAccepted');
     },
@@ skipping 100 matching lines @@
   ].forEach(function(name) {
     UserImageScreen[name] = function(value) {
       $('user-image')[name + '_'](value);
     };
   });
 
   return {
     UserImageScreen: UserImageScreen
   };
 });