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 58dc59bc3792fb0eb7a4ab3a1c02ca89d78ad586..bdf4e4e261c897b4d89ccd551de8aa9043f35501 100644
--- a/components/mus/ws/window_tree_apptest.cc
+++ b/components/mus/ws/window_tree_apptest.cc
@@ -284,6 +284,9 @@ class TestWindowTreeClientImpl : public mojom::WindowTreeClient,
     tracker()->OnEmbeddedAppDisconnected(window_id);
   }
   void OnUnembed(Id window_id) override { tracker()->OnUnembed(window_id); }
+  void OnLostCapture(Id window_id) override {
+    tracker()->OnLostCapture(window_id);
+  }
   void OnTopLevelCreated(uint32_t change_id,
                          mojom::WindowDataPtr data) override {
     tracker()->OnTopLevelCreated(change_id, std::move(data));
@@ -1770,6 +1773,32 @@ 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);
+
+  // Add the windows to the root, so that they have a WindowTreeHostImpl to
+  // handle input capture.
+  ASSERT_TRUE(ws_client1()->AddWindow(root_window_id(), window_1_1));
+  ASSERT_TRUE(ws_client1()->AddWindow(root_window_id(), window_1_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.