Add a preference to control Windows desktop search redirection.

components/search_engines/desktop_search_win.h

+// 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.
+
+#ifndef COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_WIN_H_
+#define COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_WIN_H_
+
+#include "base/feature_list.h"
+#include "base/strings/string16.h"
+
+class GURL;
+class PrefService;
+class SearchTermsData;
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
+// Values for the Windows desktop search redirection preference. ENABLED means
+// that the user has explicitly chosen to redirect desktop searches to the
+// default search engine. DISABLED means that the user has chosen not to use the
+// default search engine for desktop searches. UNSET means that no value has
+// been explicitly set for the preference, i.e. the browser should prompt the
+// user before redirecting a desktop search to the default search engine.
+enum class WindowsDesktopSearchRedirectionPref {
+  ENABLED,
+  DISABLED,
+  UNSET,
+};
+
+// Windows desktop search redirection feature.
+extern const base::Feature kWindowsDesktopSearchRedirectionFeature;

[Peter Kasting, 2015/12/01 02:23:05]

There's no need to declare this in the header as only the .cc file uses it.

[fdoray, 2015/12/02 17:28:27]

It's required if I want the feature to be controlled by about:flags. I've
included in this CL the about_flags.cc code that uses this.

+
+// Registers the Windows desktop search redirection preference into |registry|.
+void RegisterWindowsDesktopSearchRedirectionPref(
+    user_prefs::PrefRegistrySyncable* registry);
+
+// Reads the value of the Windows desktop search redirection preference from
+// |pref_service|.
+WindowsDesktopSearchRedirectionPref GetWindowsDesktopSearchRedirectionPref(
+    PrefService* pref_service);
+
+// Returns true if the Windows desktop search redirection feature is enabled.
+// When the feature is disabled, Windows desktop searches are never redirected
+// to the default search engine and the redirection preference doesn't appear
+// on the settings page.
+bool WindowsDesktopSearchRedirectionFeatureIsEnabled();
+
+// Detects whether a URL comes from a Windows Desktop search. If so, puts the
+// search terms in |search_terms| and returns true.
+bool DetectWindowsDesktopSearch(const GURL& url,
+                                const SearchTermsData& search_terms_data,
+                                base::string16* search_terms);
+
+#endif  // COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_WIN_H_