Update WM shadows for MD.

ui/wm/core/shadow.h

Index: ui/wm/core/shadow.h
diff --git a/ui/wm/core/shadow.h b/ui/wm/core/shadow.h
index 81199f848fd361d94cbc7ac006e66935f0f8ec22..e0b7a1db301c88aa440c6d48f9091a6ef4348a72 100644
--- a/ui/wm/core/shadow.h
+++ b/ui/wm/core/shadow.h
@@ -69,8 +69,13 @@ class WM_EXPORT Shadow : public ui::ImplicitAnimationObserver {
   // |content_bounds_|.
   void UpdateLayerBounds();
 
+  // Returns the "elevation" for |style_|, which dictates the shadow's display

[sky, 2016/12/07 16:39:32]

elevation doesn't really convey what this means, but then I don't have a better
suggestion.

[Evan Stade, 2016/12/07 18:55:00]

It's the metaphor that MD uses, and it works fairly well in the sense that
higher blur values mimic real-world shadows that would be cast on a more distant
surface. The visual effect is to make the thing being shadowed appear more
elevated in the Z dimension.

+  // characteristics. The elevation is proportional to the size of the blur and
+  // its offset.
+  int ElevationForStyle();
+
   // The current style, set when the transition animation starts.
-  Style style_;
+  Style style_ = STYLE_ACTIVE;
 
   // The parent layer of the shadow layer. It serves as a container accessible
   // from the outside to control the visibility of the shadow.
@@ -79,16 +84,9 @@ class WM_EXPORT Shadow : public ui::ImplicitAnimationObserver {
   // 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);
 };