Get rid of AX_LINE_BREAKS attribute to improve performance.

chrome/renderer/extensions/automation_internal_custom_bindings.cc

Index: chrome/renderer/extensions/automation_internal_custom_bindings.cc
diff --git a/chrome/renderer/extensions/automation_internal_custom_bindings.cc b/chrome/renderer/extensions/automation_internal_custom_bindings.cc
index c78f0d1382acbc51a6e91645626baad9c15c5739..5c8dc7fa754e26d1226a369c9dd12fb42a777e3c 100644
--- a/chrome/renderer/extensions/automation_internal_custom_bindings.cc
+++ b/chrome/renderer/extensions/automation_internal_custom_bindings.cc
@@ -527,6 +527,20 @@ AutomationInternalCustomBindings::AutomationInternalCustomBindings(
         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) {