More closely align palette to spec.

ash/common/system/tray/tray_popup_header_button.h

Index: ash/common/system/tray/tray_popup_header_button.h
diff --git a/ash/common/system/tray/tray_popup_header_button.h b/ash/common/system/tray/tray_popup_header_button.h
index 1777d4528ff81dff16fccb23edbe7148882eea53..a94e4d3708fa7f9586505db56048125d25ea165f 100644
--- a/ash/common/system/tray/tray_popup_header_button.h
+++ b/ash/common/system/tray/tray_popup_header_button.h
@@ -18,7 +18,7 @@ class ASH_EXPORT TrayPopupHeaderButton : public views::ToggleImageButton {
   static const char kViewClassName[];
 
   TrayPopupHeaderButton(views::ButtonListener* listener,
-                        int icon_resource_id,
+                        const gfx::ImageSkia& icon,
                         int accessible_name_id);
   TrayPopupHeaderButton(views::ButtonListener* listener,
                         int enabled_resource_id,
@@ -36,6 +36,8 @@ class ASH_EXPORT TrayPopupHeaderButton : public views::ToggleImageButton {
   // Overridden from views::CustomButton:
   void StateChanged() override;
 
+  void Initialize(const gfx::ImageSkia& icon, int accessible_name_id);
+
   DISALLOW_COPY_AND_ASSIGN(TrayPopupHeaderButton);
 };