Apply View::set_preferred_size in some more places.

ash/system/tray/system_menu_button.cc

Index: ash/system/tray/system_menu_button.cc
diff --git a/ash/system/tray/system_menu_button.cc b/ash/system/tray/system_menu_button.cc
index 9700fb3b0ae6757a4f012740d3499eb5cf6c8b85..cca6f654d19dd37d29400ff5aa5a189554e46ffd 100644
--- a/ash/system/tray/system_menu_button.cc
+++ b/ash/system/tray/system_menu_button.cc
@@ -28,9 +28,10 @@ SystemMenuButton::SystemMenuButton(views::ButtonListener* listener,
   DCHECK_EQ(normal_icon.width(), disabled_icon.width());
   DCHECK_EQ(normal_icon.height(), disabled_icon.height());
 
-  SetImage(views::Button::STATE_NORMAL, &normal_icon);
-  SetImage(views::Button::STATE_DISABLED, &disabled_icon);
+  SetImage(STATE_NORMAL, &normal_icon);
+  SetImage(STATE_DISABLED, &disabled_icon);
 
+  SetImageAlignment(ALIGN_CENTER, ALIGN_MIDDLE);
   set_preferred_size(gfx::Size(kMenuButtonSize, kMenuButtonSize));
 
   SetTooltipText(l10n_util::GetStringUTF16(accessible_name_id));