MacViews: Implement NSAccessibilityPressAction for Views with clickable roles.

ui/accessibility/ax_role_properties.h

+// Copyright 2017 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_ACCESSIBILITY_AX_ROLE_PROPERTIES_H_
+#define UI_ACCESSIBILITY_AX_ROLE_PROPERTIES_H_
+
+#include "ui/accessibility/ax_enums.h"
+#include "ui/accessibility/ax_export.h"
+
+namespace ui {
+
+// Checks if the given role should belong to a control that can respond to
+// clicks.
+AX_EXPORT bool IsRoleClickable(AXRole role);
+
+}  // namespace ui
+
+#endif  // UI_ACCESSIBILITY_AX_ROLE_PROPERTIES_H_