mus: Implement Window Server Capture

components/mus/ws/window_tree_apptest.cc

Index: components/mus/ws/window_tree_apptest.cc
diff --git a/components/mus/ws/window_tree_apptest.cc b/components/mus/ws/window_tree_apptest.cc
index 9f063d07901c91dab7ac5048de4d3026a264aadd..c2e082884af9fb1c14ec6eacbf4c8f107e15b893 100644
--- a/components/mus/ws/window_tree_apptest.cc
+++ b/components/mus/ws/window_tree_apptest.cc
@@ -298,6 +298,9 @@ class TestWindowTreeClientImpl : public mojom::WindowTreeClient,
     tracker()->OnEmbeddedAppDisconnected(window_id);
   }
   void OnUnembed() override { tracker()->OnUnembed(); }
+  void OnLostCapture(Id window_id) override {
+    tracker()->OnLostCapture(window_id);
+  }
   void OnWindowBoundsChanged(Id window_id,
                              RectPtr old_bounds,
                              RectPtr new_bounds) override {
@@ -1763,6 +1766,26 @@ TEST_F(WindowTreeAppTest, TransientWindowTracksTransientParentLifetime) {
             ChangesToDescription1(*changes1())[1]);
 }
 
+TEST_F(WindowTreeAppTest, ExplicitCapturePropagation) {
+  Id window_1_1 = ws_client1()->NewWindow(1);
+  Id window_1_2 = ws_client1()->NewWindow(2);
+  changes1()->clear();
+  // Window 1 takes capture then Window 2 takes capture.
+  // Verify that window 1 has lost capture.
+  ws1()->SetCapture(1, window_1_1);
+  ws1()->SetCapture(2, window_1_2);
+  ws_client1_->WaitForChangeCount(1);
+
+  EXPECT_EQ("OnLostCapture window=" + IdToString(window_1_1),
+            SingleChangeToDescription(*changes1()));
+  changes1()->clear();
+  ws1()->ReleaseCapture(3, window_1_2);
+  ws_client1_->WaitForChangeCount(1);
+
+  EXPECT_EQ("OnLostCapture window=" + IdToString(window_1_2),
+            SingleChangeToDescription(*changes1()));
+}
+
 // TODO(sky): need to better track changes to initial connection. For example,
 // that SetBounsdWindows/AddWindow and the like don't result in messages to the
 // originating connection.