Reduce CPU usage of download shelf UI. (both MD and pre-MD shelves)

chrome/browser/ui/views/download/download_item_view.h

Index: chrome/browser/ui/views/download/download_item_view.h
diff --git a/chrome/browser/ui/views/download/download_item_view.h b/chrome/browser/ui/views/download/download_item_view.h
index 44745249f77302f29f3213c799511a055da946c7..9afb0084969b1f7a77a267d102a6511845b4ffc0 100644
--- a/chrome/browser/ui/views/download/download_item_view.h
+++ b/chrome/browser/ui/views/download/download_item_view.h
@@ -232,6 +232,9 @@ class DownloadItemView : public views::ButtonListener,
   void AnimateStateTransition(State from, State to,
                               gfx::SlideAnimation* animation);
 
+  // Callback for |progress_timer_|.
+  void ProgressTimerFired();
+
   // The different images used for the background.
   BodyImageSet normal_body_image_set_;
   BodyImageSet hot_body_image_set_;