Adjust MD shelf app list icon for better centering.

ash/common/shelf/app_list_button.h

Index: ash/common/shelf/app_list_button.h
diff --git a/ash/common/shelf/app_list_button.h b/ash/common/shelf/app_list_button.h
index 31e50005ec2d72a113fe759983548a2d4f70fb38..0c7b553d67f37916777231ef4f206e6e208867e6 100644
--- a/ash/common/shelf/app_list_button.h
+++ b/ash/common/shelf/app_list_button.h
@@ -50,11 +50,9 @@ class ASH_EXPORT AppListButton : public views::ImageButton {
   // Toggles the active state for painting the background and schedules a paint.
   void SetDrawBackgroundAsActive(bool draw_background_as_active);
 
-  // Helper functions to paint the background and foreground of the AppList
+  // Helper function to paint the background and foreground of the AppList
   // button in Chrome OS MD.
-  void PaintBackgroundMD(gfx::Canvas* canvas);
-  void PaintForegroundMD(gfx::Canvas* canvas,
-                         const gfx::ImageSkia& foreground_image);
+  void PaintMd(gfx::Canvas* canvas);
 
   // Helper function to paint the AppList button in Chrome OS non-MD.
   void PaintAppListButton(gfx::Canvas* canvas,