Get rid of AX_LINE_BREAKS attribute to improve performance.

chrome/renderer/extensions/automation_internal_custom_bindings.cc

 // Copyright 2014 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 "chrome/renderer/extensions/automation_internal_custom_bindings.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 509 matching lines @@
         std::string role_name = ui::ToString(node->data().role);
         result.Set(v8::String::NewFromUtf8(isolate, role_name.c_str()));
       });
   RouteNodeIDFunction(
       "GetLocation", [](v8::Isolate* isolate, v8::ReturnValue<v8::Value> result,
                         TreeCache* cache, ui::AXNode* node) {
         gfx::Rect location = ComputeGlobalNodeBounds(cache, node);
         location.Offset(cache->location_offset);
         result.Set(RectToV8Object(isolate, location));
       });
+  RouteNodeIDFunction(
+      "GetLineStartOffsets",
+      [](v8::Isolate* isolate, v8::ReturnValue<v8::Value> result,
+         TreeCache* cache, ui::AXNode* node) {
+        const std::vector<int> line_starts =
+            node->GetOrComputeLineStartOffsets();
+        v8::Local<v8::Array> array_result(
+            v8::Array::New(isolate, line_starts.size()));
+        for (size_t i = 0; i < line_starts.size(); ++i) {
+          array_result->Set(static_cast<uint32_t>(i),
+                            v8::Integer::New(isolate, line_starts[i]));
+        }
+        result.Set(array_result);
+      });
   RouteNodeIDFunction("GetChildIDs", [](v8::Isolate* isolate,
                                         v8::ReturnValue<v8::Value> result,
                                         TreeCache* cache, ui::AXNode* node) {
     const std::vector<ui::AXNode*>& children = node->children();
     v8::Local<v8::Array> array_result(v8::Array::New(isolate, children.size()));
     for (size_t i = 0; i < children.size(); ++i) {
       array_result->Set(static_cast<uint32_t>(i),
                         v8::Integer::New(isolate, children[i]->id()));
     }
     result.Set(array_result);
@@ skipping 812 matching lines @@
   v8::Local<v8::Array> args(v8::Array::New(GetIsolate(), 2U));
   args->Set(0U, v8::Integer::New(GetIsolate(), tree_id));
   v8::Local<v8::Array> nodes(v8::Array::New(GetIsolate(), ids.size()));
   args->Set(1U, nodes);
   for (size_t i = 0; i < ids.size(); ++i)
     nodes->Set(i, v8::Integer::New(GetIsolate(), ids[i]));
   context()->DispatchEvent("automationInternal.onNodesRemoved", args);
 }
 
 }  // namespace extensions