frame_accessibility.h revision 1320f92c476a1ad9d19dba2a48c72b75566198e9 
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
14namespace content {
15
16class 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.
21class 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