Try |View::HandleAccessibleAction| before falling back to fixed actions.

ui/views/accessibility/ax_aura_obj_wrapper.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_ACCESSIBILITY_AX_AURA_OBJ_WRAPPER_H_
 #define UI_VIEWS_ACCESSIBILITY_AX_AURA_OBJ_WRAPPER_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/views/views_export.h"
 
 namespace ui {
+struct AXActionData;
 struct AXNodeData;
 }  // namespace ui
 
 namespace views {
 
 // An interface abstraction for Aura views that exposes the view-tree formed
 // by the implementing view types.
 class VIEWS_EXPORT AXAuraObjWrapper {
  public:
   virtual ~AXAuraObjWrapper() {}
 
   // Traversal and serialization.
   virtual AXAuraObjWrapper* GetParent() = 0;
   virtual void GetChildren(
       std::vector<AXAuraObjWrapper*>* out_children) = 0;
   virtual void Serialize(ui::AXNodeData* out_node_data) = 0;
   virtual int32_t GetID() = 0;
 
   // Actions.
   virtual void DoDefault() {}
   virtual void Focus() {}
   virtual void MakeVisible() {}
   virtual void SetSelection(int32_t start, int32_t end) {}
   virtual void ShowContextMenu() {}
+  virtual bool HandleAccessibleAction(const ui::AXActionData& action);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_ACCESSIBILITY_AX_AURA_OBJ_WRAPPER_H_