Update WM shadows for MD.

ui/wm/core/shadow.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_WM_CORE_SHADOW_H_
 #define UI_WM_CORE_SHADOW_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 51 matching lines @@
   void OnImplicitAnimationsCompleted() override;
 
  private:
   // Updates the shadow images to the current |style_|.
   void UpdateImagesForStyle();
 
   // Updates the shadow layer bounds based on the inteior inset and the current
   // |content_bounds_|.
   void UpdateLayerBounds();
 
+  // Returns the "elevation" for |style_|, which dictates the shadow's display
+  // characteristics.

[James Cook, 2016/12/05 23:38:35]

nit: Document that elevation currently means size of shadow in pixels, or at
least that shadow size is directly proportional to elevation. I think it's
important that elevation isn't just 1,2,3

[Evan Stade, 2016/12/06 00:53:21]

Done.

+  int ElevationForStyle();
+
   // The current style, set when the transition animation starts.
   Style style_;
 
   // The parent layer of the shadow layer. It serves as a container accessible
   // from the outside to control the visibility of the shadow.
   std::unique_ptr<ui::Layer> layer_;
 
   // The actual shadow layer corresponding to a cc::NinePatchLayer.
   std::unique_ptr<ui::Layer> shadow_layer_;
 
-  // Size of the current shadow image.
-  gfx::Size image_size_;
-
   // Bounds of the content that the shadow encloses.
   gfx::Rect content_bounds_;
 
-  // The interior inset of the shadow images. The content bounds of the image
-  // grid should be set to |content_bounds_| inset by this amount.
-  int interior_inset_;
-
   DISALLOW_COPY_AND_ASSIGN(Shadow);
 };
 
 }  // namespace wm
 
 #endif  // UI_WM_CORE_SHADOW_H_