Don't take a fake UGI every time we execute Javascript.

chrome/browser/prerender/prerender_browsertest.cc

 // 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 <deque>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 1614 matching lines @@
                          bool new_web_contents) const {
     WebContents* web_contents = GetActiveWebContents();
     RenderFrameHost* render_frame_host = web_contents->GetMainFrame();
     // Extra arguments in JS are ignored.
     std::string javascript = base::StringPrintf(
         "%s('%s', '%s')", javascript_function_name.c_str(),
         url.spec().c_str(), ping_url.spec().c_str());
 
     if (new_web_contents) {
       NewTabNavigationOrSwapObserver observer;
-      render_frame_host->ExecuteJavaScript(base::ASCIIToUTF16(javascript));
+      render_frame_host->
+          ExecuteJavaScriptForTests(base::ASCIIToUTF16(javascript));
       observer.Wait();
     } else {
       NavigationOrSwapObserver observer(current_browser()->tab_strip_model(),
                                         web_contents);
       render_frame_host->ExecuteJavaScript(base::ASCIIToUTF16(javascript));
       observer.Wait();
     }
   }
 
   TestPrerenderContentsFactory* prerender_contents_factory_;
@@ skipping 2770 matching lines @@
 
   // Navigate to the URL entered.
   omnibox_view->model()->AcceptInput(CURRENT_TAB, false);
 
   // Prerender should be running, but abandoned.
   EXPECT_TRUE(
       GetAutocompleteActionPredictor()->IsPrerenderAbandonedForTesting());
 }
 
 }  // namespace prerender