mash: wires up shadows for mash

ui/wm/core/shadow.cc

 // 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.
 
 #include "ui/wm/core/shadow.h"
 
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/gfx/geometry/insets.h"
@@ skipping 14 matching lines @@
 
 }  // namespace
 
 Shadow::Shadow()
     : desired_elevation_(ShadowElevation::NONE),
       rounded_corner_radius_(kDefaultRoundedCornerRadius) {}
 
 Shadow::~Shadow() {}
 
 void Shadow::Init(ShadowElevation elevation) {
+  DCHECK_NE(ShadowElevation::DEFAULT, elevation);
   desired_elevation_ = elevation;
   layer_.reset(new ui::Layer(ui::LAYER_NOT_DRAWN));
   RecreateShadowLayer();
 }
 
 void Shadow::SetContentBounds(const gfx::Rect& content_bounds) {
   // When the window moves but doesn't change size, this is a no-op. (The
   // origin stays the same in this case.)
   if (content_bounds == content_bounds_)
     return;
 
   content_bounds_ = content_bounds;
   UpdateLayerBounds();
 }
 
 void Shadow::SetElevation(ShadowElevation elevation) {
+  DCHECK_NE(ShadowElevation::DEFAULT, elevation);
   if (desired_elevation_ == elevation)
     return;
 
   desired_elevation_ = elevation;
 
   // Stop waiting for any as yet unfinished implicit animations.
   StopObservingImplicitAnimations();
 
   // The old shadow layer is the new fading out layer.
   DCHECK(shadow_layer_);
@@ skipping 110 matching lines @@
   occlusion_bounds.Inset(-margins + gfx::Insets(rounded_corner_radius_));
   shadow_layer_->UpdateNinePatchOcclusion(occlusion_bounds);
 
   // The border is the same inset as the aperture.
   shadow_layer_->UpdateNinePatchLayerBorder(
       gfx::Rect(blur_region.left(), blur_region.top(), blur_region.width(),
                 blur_region.height()));
 }
 
 }  // namespace wm