[Mac][Material Design] Update Omnibox dropdown on Mac to MD

chrome/browser/ui/cocoa/location_bar/zoom_decoration.h

Index: chrome/browser/ui/cocoa/location_bar/zoom_decoration.h
diff --git a/chrome/browser/ui/cocoa/location_bar/zoom_decoration.h b/chrome/browser/ui/cocoa/location_bar/zoom_decoration.h
index 8fd72d1d06c9fea173f6e97dd47f4f4b01daf1a6..01ad8e21b7366b1c369f0d33a6b0e5e2d83aa947 100644
--- a/chrome/browser/ui/cocoa/location_bar/zoom_decoration.h
+++ b/chrome/browser/ui/cocoa/location_bar/zoom_decoration.h
@@ -52,6 +52,9 @@ class ZoomDecoration : public ImageDecoration,
                                NSString* tooltip_string,
                                bool location_bar_is_dark);
 
+  // Overridden from LocationBarDecoration:
+  gfx::VectorIconId GetMaterialVectorIconId() override;
+
  private:
   friend ZoomDecorationTest;
 
@@ -79,6 +82,8 @@ class ZoomDecoration : public ImageDecoration,
   // The string to show for a tooltip.
   base::scoped_nsobject<NSString> tooltip_;
 
+  gfx::VectorIconId vector_icon_id_;
+
   DISALLOW_COPY_AND_ASSIGN(ZoomDecoration);
 };