One accessibility tree per frame.

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 <stdint.h>
 
 #include <vector>
@@ skipping 120 matching lines @@
 
   ~BrowserAccessibilityManager() override;
 
   void Initialize(const ui::AXTreeUpdate& initial_tree);
 
   static ui::AXTreeUpdate GetEmptyDocument();
 
   virtual void NotifyAccessibilityEvent(
       ui::AXEvent event_type, BrowserAccessibility* node) { }
 
+  // Checks whether focus has changed since the last time it was checked,
+  // taking into account whether the window has focus and which frame within
+  // the frame tree has focus. If focus has changed, calls FireFocusEvent.
+  void FireFocusEventsIfNeeded();
+
+  // Return whether or not we are currently able to fire events.
+  virtual bool CanFireEvents();
+
+  // Fire a focus event. Virtual so that some platforms can customize it,
+  // like firing a focus event on the root first, on Windows.
+  virtual void FireFocusEvent(BrowserAccessibility* node);
+
   // Return a pointer to the root of the tree, does not make a new reference.
   BrowserAccessibility* GetRoot();
 
   // Returns a pointer to the BrowserAccessibility object for a given AXNode.
   BrowserAccessibility* GetFromAXNode(const ui::AXNode* node) const;
 
   // Return a pointer to the object corresponding to the given id,
   // does not make a new reference.
   BrowserAccessibility* GetFromID(int32_t id) const;
 
@@ skipping 221 matching lines @@
   base::hash_map<int32_t, BrowserAccessibility*> id_wrapper_map_;
 
   // True if the user has initiated a navigation to another page.
   bool user_is_navigating_away_;
 
   // The on-screen keyboard state.
   OnScreenKeyboardState osk_state_;
 
   BrowserAccessibilityFindInPageInfo find_in_page_info_;
 
+  // These are only used by the root BrowserAccessibilityManager of a
+  // frame tree. Stores the last focused node and last focused manager so
+  // that when focus might have changed we can figure out whether we need
+  // to fire a focus event.
+  //
+  // NOTE: these pointers are not cleared, so they should never be
+  // dereferenced, only used for comparison.
+  BrowserAccessibility* last_focused_node_;
+  BrowserAccessibilityManager* last_focused_manager_;
+
   // The global ID of this accessibility tree.
   AXTreeIDRegistry::AXTreeID ax_tree_id_;
 
   // If this tree has a parent tree, this is the cached ID of the parent
   // node within that parent tree. It's computed as needed and cached for
   // speed so that it can be accessed quickly if it hasn't changed.
   int parent_node_id_from_parent_tree_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_