Get rid of AX_LINE_BREAKS attribute to improve performance.

ui/accessibility/ax_node.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_NODE_H_
 #define UI_ACCESSIBILITY_AX_NODE_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 51 matching lines @@
   // This is called when the AXTree no longer includes this node in the
   // tree. Reference counting is used on some platforms because the
   // operating system may hold onto a reference to an AXNode
   // object even after we're through with it, so this may decrement the
   // reference count and clear out the object's data.
   void Destroy();
 
   // Return true if this object is equal to or a descendant of |ancestor|.
   bool IsDescendantOf(AXNode* ancestor);
 
+  // Gets the text offsets where new lines start either from the node's data or
+  // by computing them and caching the result.
+  std::vector<int> GetOrComputeLineStartOffsets();
+
  private:
+  // Computes the text offset where each line starts by traversing all child
+  // leaf nodes.
+  void ComputeLineStartOffsets(std::vector<int>* line_offsets,
+                               int* end_offset) const;
+
   int index_in_parent_;
   AXNode* parent_;
   std::vector<AXNode*> children_;
   AXNodeData data_;
 };
 
 }  // namespace ui
 
 #endif  // UI_ACCESSIBILITY_AX_NODE_H_