Exclude the Assistant window from affecting occlusion.

This is to prevent it from triggering auto-picture-in-picture.

which causes the WebView in the assistant to cover the Youtube app while
it's playing a video does not trigger auto-PIP.

Bug: b/134793884
Test: Pressing the assistant button on eve and then selecting an option
Change-Id: Ia94c876d1fc67c6010b3625342e21f73568534b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1671894Reviewed-by: Tao Wu <wutao@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Eliot Courtney <edcourtney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671976}

ash/assistant/ui/assistant_container_view.cc

@@ -262,8 +262,10 @@ const char* AssistantContainerView::GetClassName() const {
 }
 
 void AssistantContainerView::AddedToWidget() {
-  GetWidget()->GetNativeWindow()->SetEventTargeter(
-      std::make_unique<AssistantContainerEventTargeter>());
+  // Exclude the Assistant window for occlusion, so it doesn't trigger auto-pip.
+  auto* window = GetWidget()->GetNativeWindow();
+  occlusion_excluder_.emplace(window);
+  window->SetEventTargeter(std::make_unique<AssistantContainerEventTargeter>());
 }
 
 ax::mojom::Role AssistantContainerView::GetAccessibleWindowRole() {

ash/assistant/ui/assistant_container_view.h

@@ -11,6 +11,8 @@
 #include "ash/assistant/ui/assistant_container_view_focus_traversable.h"
 #include "base/component_export.h"
 #include "base/macros.h"
+#include "base/optional.h"
+#include "ui/aura/window_occlusion_tracker.h"
 #include "ui/views/bubble/bubble_dialog_delegate_view.h"
 
 namespace ash {
@@ -76,6 +78,9 @@ class COMPONENT_EXPORT(ASSISTANT_UI) AssistantContainerView
   std::unique_ptr<AssistantContainerViewAnimator> animator_;
   AssistantContainerViewFocusTraversable focus_traversable_;
 
+  base::Optional<aura::WindowOcclusionTracker::ScopedExclude>
+      occlusion_excluder_;
+
   DISALLOW_COPY_AND_ASSIGN(AssistantContainerView);
 };