Add a preference to control Windows desktop search redirection.

components/search_engines/desktop_search_win.cc

 // Copyright 2015 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 "components/search_engines/detect_desktop_search_win.h"
+#include "components/search_engines/desktop_search_win.h"
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
+#include "base/prefs/pref_service.h"
 #include "base/strings/string_util.h"
+#include "components/pref_registry/pref_registry_syncable.h"
 #include "components/search_engines/prepopulated_engines.h"
 #include "components/search_engines/template_url.h"
 #include "components/search_engines/template_url_prepopulate_data.h"
 #include "net/base/url_util.h"
 
+namespace prefs {
+const char kWindowsDesktopSearchRedirectionPref[] =
+    "windows_desktop_search_redirection";
+}  // namespace prefs
+
+const base::Feature kWindowsDesktopSearchRedirectionFeature = {
+    "WindowsDesktopSearchRedirection", base::FEATURE_DISABLED_BY_DEFAULT
+};
+
+void RegisterWindowsDesktopSearchRedirectionPref(
+    user_prefs::PrefRegistrySyncable* registry) {
+  registry->RegisterBooleanPref(prefs::kWindowsDesktopSearchRedirectionPref,
+                                false);
+}
+
+bool ShouldRedirectWindowsDesktopSearchToDefaultSearchEngine(
+    PrefService* pref_service) {
+  DCHECK(pref_service);
+  return base::FeatureList::IsEnabled(
+             kWindowsDesktopSearchRedirectionFeature) &&
+         pref_service->GetBoolean(prefs::kWindowsDesktopSearchRedirectionPref);
+}
+
 bool DetectWindowsDesktopSearch(const GURL& url,
                                 const SearchTermsData& search_terms_data,
                                 base::string16* search_terms) {
   DCHECK(search_terms);
 
   scoped_ptr<TemplateURLData> template_url_data =
       TemplateURLPrepopulateData::MakeTemplateURLDataFromPrepopulatedEngine(
           TemplateURLPrepopulateData::bing);
   TemplateURL template_url(*template_url_data);
 
   if (!template_url.ExtractSearchTermsFromURL(url, search_terms_data,
                                               search_terms))
     return false;
 
   // Query parameter that tells the source of a Bing search URL, and values
   // associated with Windows desktop search.
   const char kBingSourceQueryKey[] = "form";
   const char kBingSourceDesktopText[] = "WNSGPH";
   const char kBingSourceDesktopVoice[] = "WNSBOX";
 
   for (net::QueryIterator it(url); !it.IsAtEnd(); it.Advance()) {
     // Use a case-insensitive comparison because the key is sometimes in capital
     // letters.
     if (base::EqualsCaseInsensitiveASCII(it.GetKey(), kBingSourceQueryKey)) {
-      std::string source = it.GetValue();
+      const std::string source = it.GetValue();
       if (source == kBingSourceDesktopText || source == kBingSourceDesktopVoice)
         return true;
     }
   }
 
   search_terms->clear();
   return false;
 }