Rewrite base::JSONReader to be 35-40% faster, depending on the input string.

chrome/browser/automation/testing_automation_provider.cc

Index: chrome/browser/automation/testing_automation_provider.cc
diff --git a/chrome/browser/automation/testing_automation_provider.cc b/chrome/browser/automation/testing_automation_provider.cc
index 15aae3e3be9d94ed442b3c5e98a09654978c8f29..aa5a6cbfb23498400f6dfe58e6a4f08bbf15a83f 100644
--- a/chrome/browser/automation/testing_automation_provider.cc
+++ b/chrome/browser/automation/testing_automation_provider.cc
@@ -2128,10 +2128,8 @@ void TestingAutomationProvider::GetBlockedPopupCount(int handle, int* count) {
 void TestingAutomationProvider::SendJSONRequest(int handle,
                                                 const std::string& json_request,
                                                 IPC::Message* reply_message) {
-  scoped_ptr<Value> values;
-  base::JSONReader reader;
   std::string error;
-  values.reset(reader.ReadAndReturnError(json_request,
+  scoped_ptr<Value> values(base::JSONReader::ReadAndReturnError(json_request,
       base::JSON_ALLOW_TRAILING_COMMAS, NULL, &error));
   if (!error.empty()) {
     AutomationJSONReply(this, reply_message).SendError(error);