Implement the Windows desktop search redirection feature.

components/search_engines/desktop_search_utils_win.h

Index: components/search_engines/desktop_search_utils_win.h
diff --git a/components/search_engines/desktop_search_utils_win.h b/components/search_engines/desktop_search_utils_win.h
new file mode 100644
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+++ b/components/search_engines/desktop_search_utils_win.h
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+// Copyright 2016 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.
+
+#ifndef COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_UTILS_WIN_H_
+#define COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_UTILS_WIN_H_
+
+#include "base/feature_list.h"
+#include "base/strings/string16.h"
+#include "url/gurl.h"
+
+class PrefService;
+class TemplateURLService;
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
+// Windows desktop search redirection feature. This is exposed in the header
+// file so that it can be referenced from about_flags.cc.
+extern const base::Feature kWindowsDesktopSearchRedirectionFeature;
+
+// Registers the Windows desktop search redirection preference into |registry|.
+void RegisterWindowsDesktopSearchRedirectionPref(
+    user_prefs::PrefRegistrySyncable* registry);
+
+// Replaces |url| by a default search engine URL if it is a desktop search URL
+// and these conditions are met:
+// - The Windows desktop search redirection feature is enabled.
+// - The default search engine is not Bing.
+// |should_show_infobar| is set to true if an infobar should be shown to tell
+// the user that a redirection occurred.
+void ReplaceWindowsDesktopSearchURLWithDefaultSearchURLIfNeeded(
+    PrefService* pref_service,
+    TemplateURLService* template_url_service,
+    GURL* url,
+    bool* should_show_infobar);
+
+#endif  // COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_UTILS_WIN_H_