Implement the Windows desktop search redirection feature.

components/search_engines/desktop_search_infobar_delegate_win.h

+// 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_INFOBAR_DELEGATE_WIN_H_
+#define COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_INFOBAR_DELEGATE_WIN_H_
+
+#include "base/gtest_prod_util.h"
+#include "base/macros.h"
+#include "base/strings/string16.h"
+#include "components/infobars/core/confirm_infobar_delegate.h"
+#include "url/gurl.h"
+
+class PrefService;
+
+namespace infobars {
+class InfoBarManager;
+}  // namespace infobars
+
+// The delegate for the infobar informing the user that a Windows desktop search

[Peter Kasting, 2016/01/20 03:03:01]

Nit: I'd probably just say "Informs the user that..."

Also, I probably wouldn't refer to Windows anywhere in the comments, class name,
file name, string identifier names, etc.  While callers might only use this on
Windows, there's no reason this infobar is restricted to Windows in principle. 
Basically, I would only refer to "Windows" in code that's actually
Windows-specific, i.e. has #ifdef (OS_WIN) or the like.

[fdoray, 2016/01/21 21:02:33]

Done.

+// has been redirected to the default search engine.
+class WindowsDesktopSearchInfobarDelegate : public ConfirmInfoBarDelegate {
+ public:
+  // Adds to |infobar_manager| an infobar informing the user that a Windows
+  // desktop search has been redirected to the default search engine.
+  // |default_search_engine_name| is the name of the default search engine.
+  // |search_settings_url| is the URL of the search settings. The function
+  // records in |pref_service| that the infobar has been shown.

[Peter Kasting, 2016/01/20 03:03:01]

Nit: Simpler, and more parallel to other infobars' comments:

Creates a search redirection infobar and delegate and adds the infobar to
|infobar_manager|.  Records in |pref_service| that such an infobar was shown.

[fdoray, 2016/01/21 21:02:33]

Done.

+  static void Show(infobars::InfoBarManager* infobar_manager,
+                   const base::string16& default_search_engine_name,
+                   const GURL& search_settings_url,
+                   PrefService* pref_service);
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(WindowsDesktopSearchInfobarDelegateTest,
+                           ManageSearchSettings);
+
+  WindowsDesktopSearchInfobarDelegate(
+      const base::string16& default_search_engine_name,
+      const GURL& search_settings_url);
+  virtual ~WindowsDesktopSearchInfobarDelegate();
+
+  // ConfirmInfoBarDelegate:

[Peter Kasting, 2016/01/20 03:03:01]

It seems like we really ought to have a Learn More link where we explain about
desktop search redirection and how to disable it if necessary?

[fdoray, 2016/01/21 21:02:33]

UI review decided not to have an option to disable desktop search redirection.
It is still possible to "disable" it by setting Bing as the default search
engine.

[Peter Kasting, 2016/01/22 00:38:57]

Fair enough.  Make sure you ultimately remove any flags or preferences related
to disabling this as soon as you no longer need them for kill switch purposes. 
(Often times when we decide to make something un-disablable, the relevant
switches never get removed from the codebase, and turn into a "hidden config
switch"; we don't want that sort of thing.)

+  base::string16 GetMessageText() const override;
+  int GetButtons() const override;
+  base::string16 GetButtonLabel(InfoBarButton button) const override;
+  bool Accept() override;
+
+  // infobars::InfoBarDelegate:

[Peter Kasting, 2016/01/20 03:03:01]

You don't directly subclass this class, so these overrides should be with the
ConfirmInfoBarDelegate overrides, and listed first in that group.

[fdoray, 2016/01/21 21:02:33]

Done.

+  infobars::InfoBarDelegate::InfoBarIdentifier GetIdentifier() const override;
+  void InfoBarDismissed() override;
+
+  base::string16 default_search_engine_name_;
+  GURL search_settings_url_;
+
+  // True when the infobar has been closed by clicking on the close button.
+  bool closed_by_user_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowsDesktopSearchInfobarDelegate);
+};
+
+#endif  // COMPONENTS_SEARCH_ENGINES_DESKTOP_SEARCH_INFOBAR_DELEGATE_WIN_H_