[Cleanup] Remove the obsolete Prerender field trial.

chrome/common/chrome_switches.h

 // 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.
 
 // Defines all the command-line switches used by Chrome.
 
 #ifndef CHROME_COMMON_CHROME_SWITCHES_H_
 #define CHROME_COMMON_CHROME_SWITCHES_H_
 
 #include "build/build_config.h"
@@ skipping 242 matching lines @@
 extern const char kPermissionRequestApiScope[];
 extern const char kPermissionRequestApiUrl[];
 extern const char kPpapiFlashPath[];
 extern const char kPpapiFlashVersion[];
 extern const char kPrefetchSearchResults[];
 extern const char kPrerenderFromOmnibox[];
 extern const char kPrerenderFromOmniboxSwitchValueAuto[];
 extern const char kPrerenderFromOmniboxSwitchValueDisabled[];
 extern const char kPrerenderFromOmniboxSwitchValueEnabled[];
 extern const char kPrerenderMode[];
-extern const char kPrerenderModeSwitchValueAuto[];
 extern const char kPrerenderModeSwitchValueDisabled[];
 extern const char kPrerenderModeSwitchValueEnabled[];
 extern const char kPrivetIPv6Only[];
 extern const char kProductVersion[];
 extern const char kProfileDirectory[];
 extern const char kProfilingAtStart[];
 extern const char kProfilingFile[];
 extern const char kProfilingFlush[];
 extern const char kProxyAutoDetect[];
 extern const char kProxyBypassList[];
@@ skipping 140 matching lines @@
 #if defined(OS_CHROMEOS)
 bool PowerOverlayEnabled();
 #endif
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace switches
 
 #endif  // CHROME_COMMON_CHROME_SWITCHES_H_