[Extensions] Reduce string copy in renderer/ UserScript.

extensions/renderer/programmatic_script_injector.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 "extensions/renderer/programmatic_script_injector.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/values.h"
@@ skipping 86 matching lines @@
     UserScript::RunLocation run_location) const {
   DCHECK_EQ(GetRunLocation(), run_location);
   DCHECK(params_->is_javascript);
 
   return std::vector<blink::WebScriptSource>(
       1,
       blink::WebScriptSource(
           blink::WebString::fromUTF8(params_->code), params_->file_url));
 }
 
-std::vector<std::string> ProgrammaticScriptInjector::GetCssSources(
+std::vector<blink::WebString> ProgrammaticScriptInjector::GetCssSources(
     UserScript::RunLocation run_location) const {
   DCHECK_EQ(GetRunLocation(), run_location);
   DCHECK(!params_->is_javascript);
 
-  return std::vector<std::string>(1, params_->code);
+  return std::vector<blink::WebString>(
+      1, blink::WebString::fromUTF8(params_->code));
 }
 
 void ProgrammaticScriptInjector::GetRunInfo(
     ScriptsRunInfo* scripts_run_info,
     UserScript::RunLocation run_location) const {
 }
 
 void ProgrammaticScriptInjector::OnInjectionComplete(
     std::unique_ptr<base::Value> execution_result,
     UserScript::RunLocation run_location,
@@ skipping 53 matching lines @@
   // frame deletions so nothing is left hanging).
   if (render_frame) {
     render_frame->Send(
         new ExtensionHostMsg_ExecuteCodeFinished(
             render_frame->GetRoutingID(), params_->request_id,
             error, url_, results_));
   }
 }
 
 }  // namespace extensions