Use explicit WebString conversions in remaining chrome/renderer files

chrome/renderer/chrome_render_thread_observer.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 "chrome/renderer/chrome_render_thread_observer.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <memory>
@@ skipping 245 matching lines @@
 
   field_trial_syncer_.InitFieldTrialObserving(command_line,
                                               switches::kSingleProcess);
 
   // chrome-native: is a scheme used for placeholder navigations that allow
   // UIs to be drawn with platform native widgets instead of HTML.  These pages
   // should not be accessible, and should also be treated as empty documents
   // that can commit synchronously.  No code should be runnable in these pages,
   // so it should not need to access anything nor should it allow javascript
   // URLs since it should never be visible to the user.
-  WebString native_scheme(base::ASCIIToUTF16(chrome::kChromeNativeScheme));
+  WebString native_scheme(WebString::fromASCII(chrome::kChromeNativeScheme));
   WebSecurityPolicy::registerURLSchemeAsDisplayIsolated(native_scheme);
   WebSecurityPolicy::registerURLSchemeAsEmptyDocument(native_scheme);
   WebSecurityPolicy::registerURLSchemeAsNotAllowingJavascriptURLs(
       native_scheme);
 
   thread->GetInterfaceRegistry()->AddInterface(
       visited_link_slave_->GetBindCallback());
 }
 
 ChromeRenderThreadObserver::~ChromeRenderThreadObserver() {}
@@ skipping 55 matching lines @@
 void ChromeRenderThreadObserver::OnSetFieldTrialGroup(
     const std::string& trial_name,
     const std::string& group_name) {
   field_trial_syncer_.OnSetFieldTrialGroup(trial_name, group_name);
 }
 
 const RendererContentSettingRules*
 ChromeRenderThreadObserver::content_setting_rules() const {
   return &content_setting_rules_;
 }