accessibility: Simpler AXTree root accessor.

ui/accessibility/ax_tree.h

 // Copyright 2013 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_ACCESSIBILITY_AX_TREE_H_
 #define UI_ACCESSIBILITY_AX_TREE_H_
 
 #include <set>
 
 #include "base/containers/hash_tables.h"
@@ skipping 73 matching lines @@
 // It's designed to be subclassed to implement support for native
 // accessibility APIs on a specific platform.
 class AX_EXPORT AXTree {
  public:
   AXTree();
   explicit AXTree(const AXTreeUpdate& initial_state);
   virtual ~AXTree();
 
   virtual void SetDelegate(AXTreeDelegate* delegate);
 
-  virtual AXNode* GetRoot() const;
-  virtual AXNode* GetFromId(int32 id) const;
+  AXNode* root() const { return root_; }
+
+  // Returns the AXNode with the given |id| if it is part of this AXTree.
+  AXNode* GetFromId(int32 id) const;
 
   // Returns true on success. If it returns false, it's a fatal error
   // and this tree should be destroyed, and the source of the tree update
   // should not be trusted any longer.
   virtual bool Unserialize(const AXTreeUpdate& update);
 
   // Return a multi-line indented string representation, for logging.
   std::string ToString() const;
 
   // A string describing the error from an unsuccessful Unserialize,
@@ skipping 34 matching lines @@
 
   AXTreeDelegate* delegate_;
   AXNode* root_;
   base::hash_map<int32, AXNode*> id_map_;
   std::string error_;
 };
 
 }  // namespace ui
 
 #endif  // UI_ACCESSIBILITY_AX_TREE_H_