Wires up modality for aura-mus

ui/aura/mus/window_tree_client_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/mus/window_tree_client.h"
 
 #include <stdint.h>
 
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 1030 matching lines @@
   capture_recorder.reset_capture_captured_count();
 
   // Changes originating from server should notify observers too.
   window_tree_client()->OnCaptureChanged(server_id(&child2), 0);
   EXPECT_EQ(1, capture_recorder.capture_changed_count());
   EXPECT_EQ(child2_id, capture_recorder.last_gained_capture_window_id());
   EXPECT_EQ(0, capture_recorder.last_lost_capture_window_id());
   capture_recorder.reset_capture_captured_count();
 }
 
+TEST_F(WindowTreeClientClientTest, Modal) {

[msw, 2016/10/27 18:37:37]

nit: test a successful change, sequential changes, pass-then-fail?

[sky, 2016/10/27 19:30:06]

I added a successful test. Sequential doesn't really work, nor does
pass-then-fail.

+  Window window(nullptr);
+  window.Init(ui::LAYER_NOT_DRAWN);
+  window.SetProperty(client::kModalKey, ui::MODAL_TYPE_WINDOW);
+  // Make sure server was told about it, and have the server say it failed.
+  ASSERT_TRUE(
+      window_tree()->AckSingleChangeOfType(WindowTreeChangeType::MODAL, false));
+  // Type should be back to MODAL_TYPE_NONE as the server didn't accept the
+  // change.
+  EXPECT_EQ(ui::MODAL_TYPE_NONE, window.GetProperty(client::kModalKey));
+  // There should be no more modal changes.
+  EXPECT_FALSE(
+      window_tree()->AckSingleChangeOfType(WindowTreeChangeType::MODAL, false));
+}
+
 }  // namespace aura