Makes windowmanager draw non-client area

ui/views/window/non_client_view.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_VIEWS_WINDOW_NON_CLIENT_VIEW_H_
 #define UI_VIEWS_WINDOW_NON_CLIENT_VIEW_H_
 
 #include "ui/views/view.h"
 #include "ui/views/view_targeter_delegate.h"
 
@@ skipping 55 matching lines @@
   // view should be laid out within.
   virtual gfx::Rect GetBoundsForClientView() const = 0;
 
   virtual gfx::Rect GetWindowBoundsForClientBounds(
       const gfx::Rect& client_bounds) const = 0;
 
   // This function must ask the ClientView to do a hittest.  We don't do this in
   // the parent NonClientView because that makes it more difficult to calculate
   // hittests for regions that are partially obscured by the ClientView, e.g.
   // HTSYSMENU.
+  // Return value is one of the windows HT constants (see ui/base/hit_test.h).
   virtual int NonClientHitTest(const gfx::Point& point) = 0;
+
+  // Used to make the hosting widget shaped (non-rectangular). For a
+  // rectangular window do nothing. For a shaped window update |window_mask|
+  // accordingly. |size| is the size of the widget.
   virtual void GetWindowMask(const gfx::Size& size,
                              gfx::Path* window_mask) = 0;
   virtual void ResetWindowControls() = 0;
   virtual void UpdateWindowIcon() = 0;
   virtual void UpdateWindowTitle() = 0;
+
+  // Whether the widget can be resized or maximized has changed.
   virtual void SizeConstraintsChanged() = 0;
 
   // View:
   void GetAccessibleState(ui::AXViewState* state) override;
   const char* GetClassName() const override;
 
  protected:
   NonClientFrameView();
 
   // ViewTargeterDelegate:
@@ skipping 157 matching lines @@
 
   // The accessible name of this view.
   base::string16 accessible_name_;
 
   DISALLOW_COPY_AND_ASSIGN(NonClientView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_NON_CLIENT_VIEW_H_