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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_FRAME_HOST_FRAME_ACCESSIBILITY_H_
      6 #define CONTENT_BROWSER_FRAME_HOST_FRAME_ACCESSIBILITY_H_
      7 
      8 #include <vector>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/memory/singleton.h"
     12 #include "content/common/content_export.h"
     13 
     14 namespace content {
     15 
     16 class RenderFrameHostImpl;
     17 
     18 // This singleton class maintains the mappings necessary to link child frames
     19 // and guest frames into a single tree for accessibility. This class is only
     20 // used if accessibility is enabled.
     21 class CONTENT_EXPORT FrameAccessibility {
     22  public:
     23   static FrameAccessibility* GetInstance();
     24 
     25   // Add a mapping between an accessibility node of |parent_frame_host|
     26   // and the child frame with the given frame tree node id, in the same
     27   // frame tree.
     28   void AddChildFrame(RenderFrameHostImpl* parent_frame_host,
     29                      int accessibility_node_id,
     30                      int64 child_frame_tree_node_id);
     31 
     32   // Add a mapping between an accessibility node of |parent_frame_host|
     33   // and the main frame of the guest Webcontents with the given
     34   // browser plugin instance id.
     35   void AddGuestWebContents(RenderFrameHostImpl* parent_frame_host,
     36                            int accessibility_node_id,
     37                            int browser_plugin_instance_id);
     38 
     39   // This is called when a RenderFrameHostImpl is deleted, so invalid
     40   // mappings can be removed from this data structure.
     41   void OnRenderFrameHostDestroyed(RenderFrameHostImpl* render_frame_host);
     42 
     43   // Given a parent RenderFrameHostImpl and an accessibility node id, look up
     44   // a child frame or guest frame that was previously associated with this
     45   // frame and node id. If a mapping exists, return the resulting frame if
     46   // it's valid. If it doesn't resolve to a valid RenderFrameHostImpl,
     47   // returns NULL.
     48   RenderFrameHostImpl* GetChild(RenderFrameHostImpl* parent_frame_host,
     49                                 int accessibility_node_id);
     50 
     51   // Given a RenderFrameHostImpl, check the mapping table to see if it's
     52   // the child of a node in some other frame. If so, return true and
     53   // set the parent frame and accessibility node id in the parent frame,
     54   // otherwise return false.
     55   bool GetParent(RenderFrameHostImpl* child_frame_host,
     56                  RenderFrameHostImpl** out_parent_frame_host,
     57                  int* out_accessibility_node_id);
     58 
     59  private:
     60   FrameAccessibility();
     61   virtual ~FrameAccessibility();
     62 
     63   struct ChildFrameMapping {
     64     ChildFrameMapping();
     65 
     66     RenderFrameHostImpl* parent_frame_host;
     67     int accessibility_node_id;
     68     int64 child_frame_tree_node_id;
     69     int browser_plugin_instance_id;
     70   };
     71 
     72   std::vector<ChildFrameMapping> mappings_;
     73 
     74   friend struct DefaultSingletonTraits<FrameAccessibility>;
     75 };
     76 
     77 }  // namespace content
     78 
     79 #endif  // CONTENT_BROWSER_FRAME_HOST_FRAME_ACCESSIBILITY_H_
     80