MacViews: Fix ViewTest.HandleAccelerator by faking window activation

ui/views/test/views_test_helper_mac.h

 // Copyright 2014 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 UI_VIEWS_TEST_VIEWS_TEST_HELPER_MAC_H_
 #define UI_VIEWS_TEST_VIEWS_TEST_HELPER_MAC_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/views/test/views_test_helper.h"
 
 namespace ui {
+namespace test {
+class ScopedFakeNSWindowFocus;
+}
 class ScopedAnimationDurationScaleMode;
 }
 
 namespace views {
 
 class ViewsTestHelperMac : public ViewsTestHelper {
  public:
   ViewsTestHelperMac();
   ~ViewsTestHelperMac() override;
 
   // ViewsTestHelper:
+  void SetUp() override;
   void TearDown() override;
 
  private:
   // Disable animations during tests.
   scoped_ptr<ui::ScopedAnimationDurationScaleMode> zero_duration_mode_;
 
+  // When using desktop widgets on Mac, window activation is asynchronous
+  // because the window server is involved. A window may also be deactivated by
+  // a test running in parallel, making it flaky. In non-interactive/sharded
+  // tests, |faked_focus_| is initialized, permitting a unit test to "fake" this
+  // activation, causing it to be synchronous and per-process instead.
+  scoped_ptr<ui::test::ScopedFakeNSWindowFocus> faked_focus_;
+
   DISALLOW_COPY_AND_ASSIGN(ViewsTestHelperMac);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_TEST_VIEWS_TEST_HELPER_MAC_H_