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

services/ui/ws/test_utils.h

Index: services/ui/ws/test_utils.h
diff --git a/services/ui/ws/test_utils.h b/services/ui/ws/test_utils.h
index 5f5cb302c1972a5debc079f537dd6aa688a5b629..808f16f1bf9e61d5d6baca0854aa7c674ba0ae5b 100644
--- a/services/ui/ws/test_utils.h
+++ b/services/ui/ws/test_utils.h
@@ -285,13 +285,16 @@ class TestPlatformDisplayFactory : public PlatformDisplayFactory {
 // A stub implementation of FrameGeneratorDelegate.
 class TestFrameGeneratorDelegate : public FrameGeneratorDelegate {
  public:
-  TestFrameGeneratorDelegate();
+  TestFrameGeneratorDelegate(ServerWindow* root_window);
   ~TestFrameGeneratorDelegate() override;
 
   // FrameGeneratorDelegate:
+  ServerWindow* GetActiveRootWindow() override;
   bool IsInHighContrastMode() override;
 
  private:
+  ServerWindow* root_window_;
+
   DISALLOW_COPY_AND_ASSIGN(TestFrameGeneratorDelegate);
 };