Implement hit tests/client area.

ui/aura/test/mus/test_window_tree.cc

Index: ui/aura/test/mus/test_window_tree.cc
diff --git a/ui/aura/test/mus/test_window_tree.cc b/ui/aura/test/mus/test_window_tree.cc
index a8b7fa9c0bfad6e2525c76b762f4371430a00243..c0f7ccd5564fafdbfe9ea7914fb31bf88c13878b 100644
--- a/ui/aura/test/mus/test_window_tree.cc
+++ b/ui/aura/test/mus/test_window_tree.cc
@@ -129,10 +129,14 @@ void TestWindowTree::SetWindowBounds(uint32_t change_id,
 void TestWindowTree::SetClientArea(
     uint32_t window_id,
     const gfx::Insets& insets,
-    mojo::Array<gfx::Rect> additional_client_areas) {}
+    mojo::Array<gfx::Rect> additional_client_areas) {
+  last_client_area_ = insets;
+}
 
 void TestWindowTree::SetHitTestMask(uint32_t window_id,
-                                    const base::Optional<gfx::Rect>& mask) {}
+                                    const base::Optional<gfx::Rect>& mask) {
+  last_hit_test_mask_ = mask;
+}
 
 void TestWindowTree::SetCanAcceptDrops(uint32_t window_id, bool accepts_drops) {
 }