Change google search parameter to gcx from cx in experiment

chrome/browser/search_engines/template_url.cc

 // Copyright (c) 2011 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/browser/search_engines/template_url.h"
 
 #include "base/i18n/case_conversion.h"
 #include "base/i18n/icu_string_conversions.h"
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
@@ skipping 403 matching lines @@
         string16 rlz_string = search_terms_data.GetRlzParameterValue();
         if (!rlz_string.empty()) {
           rlz_string = L"rlz=" + rlz_string + L"&";
           url.insert(i->index, UTF16ToUTF8(rlz_string));
         }
 #endif
         break;
       }
 
       case GOOGLE_SEARCH_FIELDTRIAL_GROUP: {
-#if 0  // Disable until a decision is made about what parameter to use.
         static bool use_suggest_prefix =
             base::FieldTrialList::TrialExists("SuggestHostPrefix");
         if (use_suggest_prefix) {
           static bool used_www = (base::FieldTrialList::FindFullName(
               "SuggestHostPrefix") == "Www_Prefix");
-          url.insert(i->index, used_www ? "cx=w&" : "cx=c&");
+          url.insert(i->index, used_www ? "gcx=w&" : "gcx=c&");
         }
-#endif  // 0
         break;
       }
 
       case GOOGLE_UNESCAPED_SEARCH_TERMS: {
         std::string unescaped_terms;
         base::UTF16ToCodepage(terms, input_encoding.c_str(),
                               base::OnStringConversionError::SKIP,
                               &unescaped_terms);
         url.insert(i->index, std::string(unescaped_terms.begin(),
                                          unescaped_terms.end()));
@@ skipping 310 matching lines @@
 }
 
 std::string TemplateURL::GetExtensionId() const {
   DCHECK(IsExtensionKeyword());
   return GURL(url_.url()).host();
 }
 
 bool TemplateURL::IsExtensionKeyword() const {
   return GURL(url_.url()).SchemeIs(chrome::kExtensionScheme);
 }