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

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

Index: chrome/browser/ui/views/download/download_item_view_md.h
diff --git a/chrome/browser/ui/views/download/download_item_view_md.h b/chrome/browser/ui/views/download/download_item_view_md.h
index 196c0e7e31c577e6177e5e1a5a85ff1c90993f1d..37d1dd40ba3f8793afac5460dec5c9993dc36f33 100644
--- a/chrome/browser/ui/views/download/download_item_view_md.h
+++ b/chrome/browser/ui/views/download/download_item_view_md.h
@@ -175,6 +175,9 @@ class DownloadItemViewMd : public views::ButtonListener,
     return mode_ == DANGEROUS_MODE || mode_ == MALICIOUS_MODE;
   }
 
+  // Clears or shows the warning dialog as per the state of |model_|.
+  void ToggleWarningDialog();
+
   // Reverts from dangerous mode to normal download mode.
   void ClearWarningDialog();
 
@@ -213,6 +216,9 @@ class DownloadItemViewMd : public views::ButtonListener,
                               State to,
                               gfx::SlideAnimation* animation);
 
+  // Callback for |progress_timer_|.
+  void ProgressTimerFired();
+
   // Returns the base text color.
   SkColor GetTextColor();