Split out the MSCOM pieces of BrowserAccessibilityWin into a seperate class.

ui/accessibility/platform/ax_platform_node_win.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 UI_ACCESSIBILITY_PLATFORM_AX_PLATFORM_NODE_WIN_H_
 #define UI_ACCESSIBILITY_PLATFORM_AX_PLATFORM_NODE_WIN_H_
 
 #include <atlbase.h>
 #include <atlcom.h>
 #include <oleacc.h>
@@ skipping 23 matching lines @@
     GetIAccessible2UsageObserverList();
 
 class AX_EXPORT __declspec(uuid("26f5641a-246d-457b-a96d-07f3fae6acf2"))
     AXPlatformNodeWin
     : public NON_EXPORTED_BASE(CComObjectRootEx<CComMultiThreadModel>),
       public IDispatchImpl<IAccessible2_2,
                            &IID_IAccessible2,
                            &LIBID_IAccessible2Lib>,
       public IAccessibleText,
       public IServiceProvider,
-      public NON_EXPORTED_BASE(AXPlatformNodeBase) {
+      public AXPlatformNodeBase {
  public:
   BEGIN_COM_MAP(AXPlatformNodeWin)
     COM_INTERFACE_ENTRY2(IDispatch, IAccessible2_2)
     COM_INTERFACE_ENTRY(AXPlatformNodeWin)
     COM_INTERFACE_ENTRY(IAccessible)
     COM_INTERFACE_ENTRY(IAccessible2)
     COM_INTERFACE_ENTRY(IAccessible2_2)
     COM_INTERFACE_ENTRY(IAccessibleText)
     COM_INTERFACE_ENTRY(IServiceProvider)
   END_COM_MAP()
@@ skipping 251 matching lines @@
   // should be performed on a particular child ID, rather than this object.
   // This method tries to figure out the target object from |var_id| and
   // returns a pointer to the target object if it exists, otherwise nullptr.
   // Does not return a new reference.
   AXPlatformNodeWin* GetTargetFromChildID(const VARIANT& var_id);
 };
 
 }  // namespace ui
 
 #endif  // UI_ACCESSIBILITY_PLATFORM_AX_PLATFORM_NODE_WIN_H_