mus: Allow the WM to specify the windows that can have active children.

components/mus/public/cpp/tests/window_server_test_base.h

 // 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.
 
 #ifndef COMPONENTS_MUS_PUBLIC_CPP_TESTS_WINDOW_SERVER_TEST_BASE_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_TESTS_WINDOW_SERVER_TEST_BASE_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "components/mus/public/cpp/window_tree_delegate.h"
 #include "components/mus/public/interfaces/window_tree.mojom.h"
@@ skipping 27 matching lines @@
   // explicitly quiting that, but use this for times when that is not possible.
   static bool DoRunLoopWithTimeout() WARN_UNUSED_RESULT;
 
   // Quits a run loop started by DoRunLoopWithTimeout(). Returns true on
   // success, false if a RunLoop isn't running.
   static bool QuitRunLoop() WARN_UNUSED_RESULT;
 
   WindowTreeConnection* window_manager() { return window_manager_; }
 
  protected:
+  mojom::WindowTreeHost* host() { return host_.get(); }
   WindowTreeConnection* most_recent_connection() {
     return most_recent_connection_;
   }
 
   // testing::Test:
   void SetUp() override;
   void TearDown() override;
 
   // test::ApplicationTestBase:
   mojo::ApplicationDelegate* GetApplicationDelegate() override;
@@ skipping 22 matching lines @@
   WindowTreeConnection* window_manager_;
 
   bool window_tree_connection_destroyed_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(WindowServerTestBase);
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_TESTS_WINDOW_SERVER_TEST_BASE_H_