Get rid of AX_LINE_BREAKS attribute to improve performance.

content/browser/accessibility/browser_accessibility_cocoa.mm

 // 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.
 
 #include <execinfo.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
 
@@ skipping 1004 matching lines @@
   if (!browserAccessibility_->GetIntAttribute(ui::AX_ATTR_TEXT_SEL_START,
                                               &selStart) ||
       !browserAccessibility_->GetIntAttribute(ui::AX_ATTR_TEXT_SEL_END,
                                               &selEnd)) {
     return nil;
   }
 
   if (selStart > selEnd)
     std::swap(selStart, selEnd);
 
-  const std::vector<int32_t>& line_breaks =
-      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_LINE_BREAKS);
+  const std::vector<int> line_breaks =
+      browserAccessibility_->ComputeLineBreaks();
   for (int i = 0; i < static_cast<int>(line_breaks.size()); ++i) {
     if (line_breaks[i] > selStart)
       return [NSNumber numberWithInt:i];
   }
 
   return [NSNumber numberWithInt:static_cast<int>(line_breaks.size())];
 }
 
 // Returns whether or not this node should be ignored in the
 // accessibility tree.
@@ skipping 928 matching lines @@
 }
 
 // Returns the accessibility value for the given attribute and parameter. If the
 // value isn't supported this will return nil.
 // TODO(nektar): Implement all unimplemented attributes, e.g. text markers.
 - (id)accessibilityAttributeValue:(NSString*)attribute
                      forParameter:(id)parameter {
   if (![self instanceActive])
     return nil;
 
-  const std::vector<int32_t>& line_breaks =
-      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_LINE_BREAKS);
+  const std::vector<int> line_breaks =
+      browserAccessibility_->ComputeLineBreaks();
   base::string16 value = browserAccessibility_->GetValue();
   int len = static_cast<int>(value.size());
 
   if ([attribute isEqualToString:
       NSAccessibilityStringForRangeParameterizedAttribute]) {
     return [self valueForRange:[(NSValue*)parameter rangeValue]];
   }
 
   if ([attribute
           isEqualToString:
@@ skipping 871 matching lines @@
   if (![self instanceActive])
     return [super hash];
   return browserAccessibility_->GetId();
 }
 
 - (BOOL)accessibilityShouldUseUniqueId {
   return YES;
 }
 
 @end