Aura-Mus: Enable Surface Synchronization behind flag

ui/aura/mus/window_tree_client_unittest.cc

Index: ui/aura/mus/window_tree_client_unittest.cc
diff --git a/ui/aura/mus/window_tree_client_unittest.cc b/ui/aura/mus/window_tree_client_unittest.cc
index 5d8ed27de137ba92a423aed57848b3a36a7a1869..cfb6be87b0d257baf782b4bc6eae55ba291a51e7 100644
--- a/ui/aura/mus/window_tree_client_unittest.cc
+++ b/ui/aura/mus/window_tree_client_unittest.cc
@@ -223,6 +223,41 @@ TEST_F(WindowTreeClientWmTest, SetBoundsFailedLocalSurfaceId) {
   EXPECT_FALSE(window_mus->GetLocalSurfaceId().is_valid());
 }
 
+// Verifies that a ClientSurfaceEmbedder is created for a window once it has
+// a bounds, a valid FrameSinkId and is visible.
+TEST_F(WindowTreeClientWmTest, ClientSurfaceEmbedderOnValidEmbedding) {
+  Window window(nullptr);
+  // TOP_LEVEL_IN_WM and EMBED_IN_OWNER windows allocate cc::LocalSurfaceIds
+  // when their sizes change.
+  window.SetProperty(aura::client::kEmbedType,
+                     aura::client::WindowEmbedType::EMBED_IN_OWNER);
+  window.Init(ui::LAYER_NOT_DRAWN);
+
+  const gfx::Rect new_bounds(gfx::Rect(0, 0, 100, 100));
+  ASSERT_NE(new_bounds, window.bounds());
+  window.SetBounds(new_bounds);
+  EXPECT_EQ(new_bounds, window.bounds());
+  WindowMus* window_mus = WindowMus::Get(&window);
+  ASSERT_NE(nullptr, window_mus);
+  EXPECT_TRUE(window_mus->GetLocalSurfaceId().is_valid());
+
+  // An ClientSurfaceEmbedder isn't created UNTIL the window is visible and has
+  // a valid FrameSinkId.
+  WindowPortMus* window_port_mus = WindowPortMus::Get(&window);
+  ASSERT_NE(nullptr, window_port_mus);
+  EXPECT_EQ(nullptr, window_port_mus->client_surface_embedder());
+
+  // The window is now visible, but doesn't yet have a FrameSinkId.
+  window.Show();
+  EXPECT_EQ(nullptr, window_port_mus->client_surface_embedder());
+
+  // Now that the window has a valid FrameSinkId, it can embed the client in a
+  // CompositorFrame.
+  window_tree_client()->OnFrameSinkIdAllocated(server_id(&window),
+                                               cc::FrameSinkId(1, 1));
+  EXPECT_NE(nullptr, window_port_mus->client_surface_embedder());
+}
+
 // Verifies that the cc::LocalSurfaceId generated by an embedder changes when
 // the size changes, but not when the position changes.
 TEST_F(WindowTreeClientWmTest, SetBoundsLocalSurfaceIdChanges) {