exo: Run exo in mus+ash

components/exo/test/exo_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_EXO_TEST_EXO_TEST_BASE_H_
 #define COMPONENTS_EXO_TEST_EXO_TEST_BASE_H_
 
 #include <memory>
 
 #include "ash/test/ash_test_base.h"
 #include "base/macros.h"
 
 namespace exo {
+class WMHelper;
+
 namespace test {
 class ExoTestHelper;
 
 class ExoTestBase : public ash::test::AshTestBase {
  public:
   ExoTestBase();
   ~ExoTestBase() override;
 
   // Overridden from testing::Test:
   void SetUp() override;
   void TearDown() override;
 
   ExoTestHelper* exo_test_helper() { return exo_test_helper_.get(); }
 
  private:
   std::unique_ptr<ExoTestHelper> exo_test_helper_;
+  std::unique_ptr<WMHelper> wm_helper_;
 
   DISALLOW_COPY_AND_ASSIGN(ExoTestBase);
 };
 
 }  // namespace test
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_TEST_EXO_TEST_BASE_H_