Add ink drop masking to TrayBackgroundView

ui/views/animation/ink_drop_impl.cc

Index: ui/views/animation/ink_drop_impl.cc
diff --git a/ui/views/animation/ink_drop_impl.cc b/ui/views/animation/ink_drop_impl.cc
index b61932fe6cd6e020bf778cbd4cf1e198403c9a82..01b392896552051bceda44aa4da4bdf53e19a0f6 100644
--- a/ui/views/animation/ink_drop_impl.cc
+++ b/ui/views/animation/ink_drop_impl.cc
@@ -575,7 +575,7 @@ InkDropImpl::HighlightStateFactory::CreateVisibleState(
   return nullptr;
 }
 
-InkDropImpl::InkDropImpl(InkDropHost* ink_drop_host)
+InkDropImpl::InkDropImpl(InkDropHost* ink_drop_host, const gfx::Size& host_size)
     : ink_drop_host_(ink_drop_host),
       root_layer_(new ui::Layer(ui::LAYER_NOT_DRAWN)),
       root_layer_added_to_host_(false),
@@ -585,6 +585,7 @@ InkDropImpl::InkDropImpl(InkDropHost* ink_drop_host)
       is_focused_(false),
       exiting_highlight_state_(false),
       destroying_(false) {
+  root_layer_->SetBounds(gfx::Rect(host_size));
   SetAutoHighlightMode(AutoHighlightMode::NONE);
   root_layer_->set_name("InkDropImpl:RootLayer");
 }
@@ -620,6 +621,13 @@ void InkDropImpl::SetAutoHighlightMode(AutoHighlightMode auto_highlight_mode) {
   SetHighlightState(highlight_state_factory_->CreateStartState());
 }
 
+void InkDropImpl::HostSizeChanged(const gfx::Size& new_size) {
+  // |root_layer_| should fill the entire host because it affects the clipping
+  // when a mask layer is applied to it. This will not affect clipping if no
+  // mask layer is set.
+  root_layer_->SetBounds(gfx::Rect(new_size));
+}
+
 InkDropState InkDropImpl::GetTargetInkDropState() const {
   if (!ink_drop_ripple_)
     return InkDropState::HIDDEN;