mus: Allow SetModal to fail gracefully

components/mus/public/cpp/tests/window_tree_client_impl_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 "components/mus/public/cpp/lib/window_tree_client_impl.h"
 
 #include <stdint.h>
 
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 320 matching lines @@
   // most recent visible from server.
   setup.window_tree_client()->OnChangeCompleted(change_id, false);
   EXPECT_EQ(server_changed_visible, root->visible());
 
   // Simulate server changing back to original visible. Should take immediately.
   setup.window_tree_client()->OnWindowVisibilityChanged(root->id(),
                                                         original_visible);
   EXPECT_EQ(original_visible, root->visible());
 }
 
+// Verifies |is_modal| is reverted if the server replied that the change failed.
+TEST_F(WindowTreeClientImplTest, SetModalFailed) {
+  WindowTreeSetup setup;
+  Window* root = setup.GetFirstRoot();
+  ASSERT_TRUE(root);
+  EXPECT_FALSE(root->is_modal());
+  root->SetModal();
+  uint32_t change_id;
+  ASSERT_TRUE(setup.window_tree()->GetAndClearChangeId(&change_id));
+  EXPECT_TRUE(root->is_modal());
+  setup.window_tree_client()->OnChangeCompleted(change_id, false);
+  EXPECT_FALSE(root->is_modal());
+}
+
 TEST_F(WindowTreeClientImplTest, InputEventBasic) {
   WindowTreeSetup setup;
   Window* root = setup.GetFirstRoot();
   ASSERT_TRUE(root);
 
   TestInputEventHandler event_handler;
   root->set_input_event_handler(&event_handler);
 
   scoped_ptr<ui::Event> ui_event(
       new ui::MouseEvent(ui::ET_MOUSE_MOVED, gfx::Point(), gfx::Point(),
@@ skipping 453 matching lines @@
 
   setup.window_tree_client()->OnChangeCompleted(change_id2, false);
   EXPECT_FALSE(child->HasCapture());
   EXPECT_TRUE(root->HasCapture());
 
   setup.window_tree_client()->OnLostCapture(root->id());
   EXPECT_FALSE(root->HasCapture());
 }
 
 }  // namespace mus