Apply new MD shadows to CrOS tray bubbles.

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 "base/lazy_instance.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
@@ skipping 135 matching lines @@
   if (style_ == STYLE_INACTIVE) {
     UpdateImagesForStyle();
     // Opacity is baked into inactive image, so set fully opaque.
     shadow_layer_->SetOpacity(1.0f);
   }
 }
 
 void Shadow::UpdateImagesForStyle() {
   const ShadowDetails& details = GetDetailsForElevation(ElevationForStyle());
   shadow_layer_->UpdateNinePatchLayerImage(details.ninebox_image);
-  // The ninebox grid is defined in terms of the image size. The shadow blurs in
-  // both inward and outward directions from the edge of the contents, so the
-  // aperture goes further inside the image than the shadow margins (which
-  // represent exterior blur).
-  gfx::Rect aperture(details.ninebox_image.size());
-  gfx::Insets blur_region = gfx::ShadowValue::GetBlurRegion(details.values) +
-                            gfx::Insets(kRoundedCornerRadius);
-  aperture.Inset(blur_region);
-  shadow_layer_->UpdateNinePatchLayerAperture(aperture);
   UpdateLayerBounds();
 }
 
 void Shadow::UpdateLayerBounds() {
   const ShadowDetails& details = GetDetailsForElevation(ElevationForStyle());
   // Shadow margins are negative, so this expands outwards from
   // |content_bounds_|.
   const gfx::Insets margins = gfx::ShadowValue::GetMargin(details.values);
   gfx::Rect layer_bounds = content_bounds_;
   layer_bounds.Inset(margins);
@@ skipping 11 matching lines @@
   // larger than the shadow layer. When the shadow layer is too small, shrink
   // the dimensions proportionally.
   gfx::Insets blur_region = gfx::ShadowValue::GetBlurRegion(details.values) +
                             gfx::Insets(kRoundedCornerRadius);
   int border_w = std::min(blur_region.width(), shadow_layer_bounds.width());
   int border_x = border_w * blur_region.left() / blur_region.width();
   int border_h = std::min(blur_region.height(), shadow_layer_bounds.height());
   int border_y = border_h * blur_region.top() / blur_region.height();
   shadow_layer_->UpdateNinePatchLayerBorder(
       gfx::Rect(border_x, border_y, border_w, border_h));
+
+  // The ninebox grid is defined in terms of the image size. The shadow blurs in
+  // both inward and outward directions from the edge of the contents, so the
+  // aperture goes further inside the image than the shadow margins (which
+  // represent exterior blur).
+  gfx::Rect aperture(details.ninebox_image.size());
+  // The insets for the aperture are nominally |blur_region| but we need to
+  // resize them if the contents are too small.
+  // TODO(estade): by cutting out parts of ninebox, we lose the smooth
+  // horizontal or vertical transition. This isn't very noticeable, but we may
+  // need to address it by using a separate shadow layer for each ShadowValue,
+  // by adjusting the shadow for very small windows, or other means.

[James Cook, 2016/12/09 19:40:13]

Aside: I vaguely recall from long ago that we decided not to worry about very
small windows (like 20x20 or whatever) since they don't occur in practice. I'm
not sure how small is "very small" for the purposes of this code.

[Evan Stade, 2016/12/09 21:09:18]

I ran into this problem for the message center bubble when I have no messages
(at which point it's only 50px tall). It's not super high priority imo because
it is pretty rare, as you say --- you can't make a browser window short enough
to see it. That said, I might not want to launch this to stable like this, but
if we don't have a great solution by then we can always just revert the shadow
change only for the notification bubble.

+  aperture.Inset(gfx::Insets(border_y, border_x, border_h - border_y,
+                             border_w - border_x));
+  shadow_layer_->UpdateNinePatchLayerAperture(aperture);
 }
 
 int Shadow::ElevationForStyle() {
   switch (style_) {
     case STYLE_ACTIVE:
       return 24;
     case STYLE_INACTIVE:
       return 8;
     case STYLE_SMALL:
       return 6;
   }
   NOTREACHED();
   return 0;
 }
 
 }  // namespace wm