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

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

Index: chrome/browser/resources/chromeos/login/oobe_screen_user_image.js
diff --git a/chrome/browser/resources/chromeos/login/oobe_screen_user_image.js b/chrome/browser/resources/chromeos/login/oobe_screen_user_image.js
index b3b39e0047e2a01eeaa9916bb25884b2a4317373..479b9aa06c656f3043e82b4c1675f7f11ce2d173 100644
--- a/chrome/browser/resources/chromeos/login/oobe_screen_user_image.js
+++ b/chrome/browser/resources/chromeos/login/oobe_screen_user_image.js
@@ -211,6 +211,7 @@ cr.define('oobe', function() {
     onBeforeShow: function(data) {
       Oobe.getInstance().headerHidden = true;
       $('user-image-grid').updateAndFocus();
+      chrome.send('onUserImageScreenShown', [(new Date()).getTime()/1000]);

[zel, 2011/10/20 21:57:44]

you should not use time from JS side here, you should get current time on C++
side when this even arrives.

[Ivan Korotkov, 2011/10/21 07:52:00]

Why? I'm interested in the delay between Show() is called in C++ code and the
Oobe.showScreen call is made (this delay is caused by an amount of extensions
being synced at the same time, etc).

[Ivan Korotkov, 2011/10/21 12:29:52]

Hm, ok, as discussed offline it's better to use a consistent clock source, so
moving this to C++ side.

     },
 
     /**