mus: Let clients set the cursor of their window.

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 70613fc1f9692880ce6c8c509a7a9f0e12b47f1e..8d04142443245938c448aa0613e52daa070df507 100644
--- a/components/mus/ws/window_tree_apptest.cc
+++ b/components/mus/ws/window_tree_apptest.cc
@@ -353,6 +353,10 @@ class TestWindowTreeClientImpl : public mojom::WindowTreeClient,
   }
   // TODO(sky): add testing coverage.
   void OnWindowFocused(uint32_t focused_window_id) override {}
+  void OnWindowCursorChanged(uint32 window_id,
+                             mojom::Cursor cursor_id) override {
+    tracker_.OnWindowCursorChanged(window_id, cursor_id);
+  }
   void OnChangeCompleted(uint32_t change_id, bool success) override {
     if (waiting_change_id_ == change_id && change_completed_run_loop_) {
       on_change_completed_result_ = success;
@@ -1415,6 +1419,20 @@ TEST_F(WindowTreeAppTest, SetWindowVisibility) {
   }
 }
 
+// Test that we hear the cursor change in other connections.
+TEST_F(WindowTreeAppTest, SetCursor) {
+  // Get a second connection to listen in.
+  ASSERT_NO_FATAL_FAILURE(EstablishSecondConnection(true));
+  Id window_1_1 = BuildWindowId(connection_id_1(), 1);
+  changes2()->clear();
+
+  ws1()->SetStandardCursor(window_1_1, mojom::Cursor::CURSOR_IBEAM);
+  ws_client2_->WaitForChangeCount(1u);
+
+  EXPECT_EQ("CursorChanged id=" + IdToString(window_1_1) + " cursor_id=4",
+            SingleChangeToDescription(*changes2()));
+}
+
 // Assertions for SetWindowVisibility sending notifications.
 TEST_F(WindowTreeAppTest, SetWindowVisibilityNotifications) {
   // Create 1,1 and 1,2. 1,2 is made a child of 1,1 and 1,1 a child of the root.