Implement the Windows desktop search redirection feature.

components/search_engines/desktop_search_utils.h

Index: components/search_engines/desktop_search_utils.h
diff --git a/components/search_engines/desktop_search_utils.h b/components/search_engines/desktop_search_utils.h
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+++ b/components/search_engines/desktop_search_utils.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_H_
+#define COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_UTILS_H_
+
+#include "base/feature_list.h"
+#include "base/strings/string16.h"
+#include "url/gurl.h"
+
+class PrefService;
+class TemplateURLService;
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
+namespace prefs {
+// Name of the preference keeping track of whether the desktop search
+// redirection infobar has been shown.
+extern const char kDesktopSearchRedirectionInfobarShownPref[];
+}
+
+// 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 kDesktopSearchRedirectionFeature;
+
+// Registers the preference keeping track of whether the desktop search
+// redirection infobar has been shown.
+void RegisterDesktopSearchRedirectionPref(
+    user_prefs::PrefRegistrySyncable* registry);
+
+// Replaces |url| by a default search engine URL if:
+// - |url| is a desktop search URL.
+// - The desktop search redirection feature is enabled.
+// - The default search engine is not Bing.
+// Returns true if an infobar should be shown to tell the user about the
+// redirection.
+bool ReplaceDesktopSearchURLWithDefaultSearchURLIfNeeded(
+    const PrefService* pref_service,
+    TemplateURLService* template_url_service,
+    GURL* url);
+
+#endif  // COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_UTILS_H_