Make views Slider accessible on Chrome OS

ui/base/accessibility/accessibility_types.h

 // Copyright (c) 2011 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_BASE_ACCESSIBILITY_ACCESSIBILITY_TYPES_H_
 #define UI_BASE_ACCESSIBILITY_ACCESSIBILITY_TYPES_H_
 #pragma once
 
 #include "base/basictypes.h"
 
@@ skipping 57 matching lines @@
     ROLE_OUTLINE,
     ROLE_OUTLINEITEM,
     ROLE_PAGETAB,
     ROLE_PAGETABLIST,
     ROLE_PANE,
     ROLE_PROGRESSBAR,
     ROLE_PUSHBUTTON,
     ROLE_RADIOBUTTON,
     ROLE_SCROLLBAR,
     ROLE_SEPARATOR,
+    ROLE_SLIDER,
     ROLE_STATICTEXT,
     ROLE_TEXT,
     ROLE_TITLEBAR,
     ROLE_TOOLBAR,
     ROLE_WINDOW
   };
 
   // This defines an enumeration of the supported accessibility events in our
   // Views (e.g. used in View::NotifyAccessibilityEvent). Any interface using
   // events must provide a conversion to its own events (see e.g.
@@ skipping 13 matching lines @@
 
  private:
   // Do not instantiate this class.
   AccessibilityTypes() {}
   ~AccessibilityTypes() {}
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_ACCESSIBILITY_ACCESSIBILITY_TYPES_H_