[Refactor] Cache the views::Widget* that the FrameMaximizeButton acts on

ash/wm/caption_buttons/frame_caption_button_container_view.h

Index: ash/wm/caption_buttons/frame_caption_button_container_view.h
diff --git a/ash/wm/caption_buttons/frame_caption_button_container_view.h b/ash/wm/caption_buttons/frame_caption_button_container_view.h
index c9590c6655a2c3607a97b2b84009d6fda6db95a1..884d2737e35f40641d4eaeddc8e413797734b716 100644
--- a/ash/wm/caption_buttons/frame_caption_button_container_view.h
+++ b/ash/wm/caption_buttons/frame_caption_button_container_view.h
@@ -12,7 +12,6 @@
 
 namespace views {
 class CustomButton;
-class NonClientFrameView;
 class Widget;
 }
 
@@ -49,10 +48,7 @@ class ASH_EXPORT FrameCaptionButtonContainerView
   // that the caption buttons act on.
   // |minimize_allowed| indicates whether the frame can be minimized (either via
   // the maximize/restore button or via a dedicated button).
-  // TODO(pkotwicz): Remove the |frame_view| parameter once FrameMaximizeButton
-  // is refactored to take in a views::Widget instead.
-  FrameCaptionButtonContainerView(views::NonClientFrameView* frame_view,
-                                  views::Widget* frame,
+  FrameCaptionButtonContainerView(views::Widget* frame,
                                   MinimizeAllowed minimize_allowed);
   virtual ~FrameCaptionButtonContainerView();