cc: 9patch: fix shadow scaling issue

mash/wm/shadow.cc

Index: mash/wm/shadow.cc
diff --git a/mash/wm/shadow.cc b/mash/wm/shadow.cc
index 5de5c452fa1296f2f1d320d75f01319949f77724..26262afc54f4b481d8efd9f7c3ccefcfed8c02c1 100644
--- a/mash/wm/shadow.cc
+++ b/mash/wm/shadow.cc
@@ -195,12 +195,23 @@ void Shadow::UpdateLayerBounds() {
   int aperture = GetShadowApertureForStyle(style_);
   int aperture_x = std::min(aperture, layer_bounds.width() / 2);
   int aperture_y = std::min(aperture, layer_bounds.height() / 2);
-  shadow_layer_->UpdateNinePatchLayerAperture(
-      gfx::Rect(aperture_x, aperture_y,
-                image_size_.width() - aperture_x * 2,
-                image_size_.height() - aperture_y * 2));
-  shadow_layer_->UpdateNinePatchOcclusion(
-      content_bounds_ + gfx::Vector2d(interior_inset_, interior_inset_));
+  gfx::Rect aperture_rect(aperture_x, aperture_y,
+                          image_size_.width() - aperture_x * 2,
+                          image_size_.height() - aperture_y * 2);
+
+  shadow_layer_->UpdateNinePatchLayerAperture(aperture_rect);
+  shadow_layer_->UpdateNinePatchLayerBorder(
+      gfx::Rect(aperture_x, aperture_y, aperture_x * 2, aperture_y * 2));
+
+  // The content bounds in the shadow's layer space are offsetted by
+  // |interior_inset_| and also shrinked by the aperture's rectangle to
+  // include rounding corners overdrawing the window's content.
+  gfx::Rect content_bounds(
+      content_bounds_.x() + interior_inset_ + aperture_rect.width(),
+      content_bounds_.y() + interior_inset_ + aperture_rect.height(),
+      content_bounds_.width() - 2 * aperture_rect.width(),
+      content_bounds_.height() - 2 * aperture_rect.height());
+  shadow_layer_->UpdateNinePatchOcclusion(content_bounds);
 }
 
 void Shadow::OnWindowDestroyed(mus::Window* window) {