Reland of "Mustash: Ensure surfaces submitted to Mus by WM and embedders contain Surfaces with embe…

services/ui/ws/test_utils.cc

Index: services/ui/ws/test_utils.cc
diff --git a/services/ui/ws/test_utils.cc b/services/ui/ws/test_utils.cc
index 947f0898323dedc43f468db10c834b8ab244fd38..5c50fae5d6c7fb6a3fd0e1feed5bc40dcd6b074d 100644
--- a/services/ui/ws/test_utils.cc
+++ b/services/ui/ws/test_utils.cc
@@ -151,10 +151,16 @@ TestPlatformDisplayFactory::CreatePlatformDisplay(
 
 // TestFrameGeneratorDelegate -------------------------------------------------
 
-TestFrameGeneratorDelegate::TestFrameGeneratorDelegate() {}
+TestFrameGeneratorDelegate::TestFrameGeneratorDelegate(
+    ServerWindow* root_window)
+    : root_window_(root_window) {}
 
 TestFrameGeneratorDelegate::~TestFrameGeneratorDelegate() {}
 
+ServerWindow* TestFrameGeneratorDelegate::GetActiveRootWindow() {
+  return root_window_;
+}
+
 bool TestFrameGeneratorDelegate::IsInHighContrastMode() {
   return false;
 }