mus Window Server: implement event capture

components/mus/ws/window_tree_unittest.cc

Index: components/mus/ws/window_tree_unittest.cc
diff --git a/components/mus/ws/window_tree_unittest.cc b/components/mus/ws/window_tree_unittest.cc
index 351154dd4098ff78dfd0fde465d021beafc4aaf5..8eea4521d5a231ac4c1a5a58828a10707c275897 100644
--- a/components/mus/ws/window_tree_unittest.cc
+++ b/components/mus/ws/window_tree_unittest.cc
@@ -133,6 +133,7 @@ class TestWindowTreeClient : public mus::mojom::WindowTreeClient {
     tracker_.OnEmbeddedAppDisconnected(window);
   }
   void OnUnembed(Id window_id) override { tracker_.OnUnembed(window_id); }
+  void OnLostCapture(Id window_id) override {}
   void OnTopLevelCreated(uint32_t change_id,
                          mojom::WindowDataPtr data) override {
     tracker_.OnTopLevelCreated(change_id, std::move(data));
@@ -323,6 +324,8 @@ class TestDisplayManager : public DisplayManager {
                      const gfx::Rect& bounds) override {}
   void SetViewportSize(const gfx::Size& size) override {}
   void SetTitle(const base::string16& title) override {}
+  void SetCapture() override {}
+  void ReleaseCapture() override {}
   void SetCursorById(int32_t cursor) override { *cursor_id_storage_ = cursor; }
   mojom::Rotation GetRotation() override { return mojom::Rotation::VALUE_0; }
   const mojom::ViewportMetrics& GetViewportMetrics() override {
@@ -898,5 +901,50 @@ TEST_F(WindowTreeTest, NewTopLevelWindow) {
   EXPECT_FALSE(embed_window->visible());
 }
 
+// Tests that setting capture only works while an input event is being
+// processed, and the only the capture window can release capture.
+TEST_F(WindowTreeTest, ExplicitSetCapture) {
+  TestWindowTreeClient* embed_connection = nullptr;
+  WindowTreeImpl* window_tree_connection = nullptr;
+  ServerWindow* window = nullptr;
+  EXPECT_NO_FATAL_FAILURE(
+      SetupEventTargeting(&embed_connection, &window_tree_connection, &window));
+  const ServerWindow* root_window = *window_tree_connection->roots().begin();
+  window_tree_connection->AddWindow(
+      FirstRootId(window_tree_connection),
+      ClientWindowIdForWindow(window_tree_connection, window));
+  window->SetBounds(gfx::Rect(0, 0, 100, 100));
+  ASSERT_TRUE(window_tree_connection->GetHost(window));
+
+  // Setting capture should fail when there are no active events
+  mojom::WindowTree* mojom_window_tree =
+      static_cast<mojom::WindowTree*>(window_tree_connection);
+  uint32_t change_id = 42;
+  mojom_window_tree->SetCapture(change_id, WindowIdToTransportId(window->id()));
+  WindowTreeHostImpl* host = window_tree_connection->GetHost(window);
+  EXPECT_NE(window, host->GetCaptureWindow());
+
+  // Setting capture after the event is acknowledged should fail
+  DispatchEventAndAckImmediately(CreatePointerDownEvent(10, 10));
+  mojom_window_tree->SetCapture(++change_id,
+                                WindowIdToTransportId(window->id()));
+  EXPECT_NE(window, host->GetCaptureWindow());
+
+  // Settings while the event is being process should pass
+  DispatchEventWithoutAck(CreatePointerDownEvent(10, 10));
+  mojom_window_tree->SetCapture(++change_id,
+                                WindowIdToTransportId(window->id()));
+  EXPECT_EQ(window, host->GetCaptureWindow());
+  AckPreviousEvent();
+
+  // Only the capture window should be able to release capture
+  mojom_window_tree->ReleaseCapture(++change_id,
+                                    WindowIdToTransportId(root_window->id()));
+  EXPECT_EQ(window, host->GetCaptureWindow());
+  mojom_window_tree->ReleaseCapture(++change_id,
+                                    WindowIdToTransportId(window->id()));
+  EXPECT_EQ(nullptr, host->GetCaptureWindow());
+}
+
 }  // namespace ws
 }  // namespace mus