Implement initial support for nesting one ax tree in another.

content/browser/accessibility/browser_accessibility_manager.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
 #define CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
 
 #include <vector>
 
 #include "base/containers/hash_tables.h"
@@ skipping 160 matching lines @@
   // AXTreeDelegate implementation.
   virtual void OnNodeWillBeDeleted(ui::AXNode* node) OVERRIDE;
   virtual void OnNodeCreated(ui::AXNode* node) OVERRIDE;
   virtual void OnNodeChanged(ui::AXNode* node) OVERRIDE;
   virtual void OnNodeCreationFinished(ui::AXNode* node) OVERRIDE;
   virtual void OnNodeChangeFinished(ui::AXNode* node) OVERRIDE;
   virtual void OnRootChanged(ui::AXNode* new_root) OVERRIDE {}
 
   BrowserAccessibilityDelegate* delegate() const { return delegate_; }
 
+  // Frame tree support.
+  void SetParentFrameIds(uint32 parent_frame_frame_id,
+                         uint32 parent_frame_node_id);
+  BrowserAccessibility* GetCrossFrameParent();
+
  protected:
   BrowserAccessibilityManager(
       BrowserAccessibilityDelegate* delegate,
       BrowserAccessibilityFactory* factory);
 
   BrowserAccessibilityManager(
       const ui::AXTreeUpdate& initial_tree,
       BrowserAccessibilityDelegate* delegate,
       BrowserAccessibilityFactory* factory);
 
@@ skipping 44 matching lines @@
 
   // The underlying tree of accessibility objects.
   scoped_ptr<ui::AXTree> tree_;
 
   // The node that currently has focus.
   ui::AXNode* focus_;
 
   // A mapping from a node id to its wrapper of type BrowserAccessibility.
   base::hash_map<int32, BrowserAccessibility*> id_wrapper_map_;
 
+  // This and the following field are set if this tree's frame is the child
+  // of another frame.
+  //
+  // The id of the parent frame, which can be mapped to another
+  // BrowserAccessibilityManager using FrameTreeAccessibility.
+  uint32 parent_frame_frame_id_;

[aboxhall, 2014/05/06 15:41:27]

I'm wondering whether this and the below should be a struct. Possibly not, just
an idea.

+
+  // If |parent_frame_frame_id_| is not kNoFrameId, then this is the
+  // id of the hosting node within the parent frame.
+  uint32 parent_frame_node_id_;
+
   // The on-screen keyboard state.
   OnScreenKeyboardState osk_state_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_