A few more cleanups to overview mode code related to the pre-MD version.

ash/resources/ash_resources.grd

Index: ash/resources/ash_resources.grd
diff --git a/ash/resources/ash_resources.grd b/ash/resources/ash_resources.grd
index 4b344831742b4bdc07ca6dda93d85d69750e1553..b550bf30738d29c2825374c392dcf73f639f730e 100644
--- a/ash/resources/ash_resources.grd
+++ b/ash/resources/ash_resources.grd
@@ -185,10 +185,6 @@
       <structure type="chrome_scaled_image" name="IDR_AURA_WINDOW_HEADER_SHADE_INACTIVE_RIGHT" file="common/window_header_shade_right_inactive.png" />
       <structure type="chrome_scaled_image" name="IDR_AURA_WINDOW_HEADER_SHADE_INACTIVE_TOP" file="common/window_header_shade_top_inactive.png" />
 
-      <structure type="chrome_scaled_image" name="IDR_AURA_WINDOW_OVERVIEW_CLOSE" file="common/window_overview_close_normal.png" />
-      <structure type="chrome_scaled_image" name="IDR_AURA_WINDOW_OVERVIEW_CLOSE_H" file="common/window_overview_close_hover.png" />
-      <structure type="chrome_scaled_image" name="IDR_AURA_WINDOW_OVERVIEW_CLOSE_P" file="common/window_overview_close_pressed.png" />
-
       <structure type="chrome_scaled_image" name="IDR_AVATAR_HOLDER" file="cros/avatar_holder.png" />
       <structure type="chrome_scaled_image" name="IDR_AVATAR_HOLDER_MASK" file="cros/avatar_holder_mask.png" />
     </structures>