Make application shortcuts point to app_host.exe, install App Host during app installation.

chrome/browser/extensions/app_host_installer.h

+// Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_H_
+#define CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_H_
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+
+namespace extensions {
+
+class Extension;
+class AppHostInstallerImpl;
+
+class AppHostInstaller {
+ public:
+  AppHostInstaller();
+  ~AppHostInstaller();
+
+  // Installs App Host, then calls (directly or via post) |next_step|

[erikwright (departed), 2012/10/05 02:21:56]

Installs the App Host if it is required and not present for the given extension
on the current platform.

Calls |completion_callback| after checks and installation (if necessary) are
complete, with a boolean which will be false iff the installation was required
but failed.

[huangs, 2012/10/05 19:46:08]

Done.

+  // to proceed with installation, on the caller thread.
+  // |next_step| takes a bool parameter to be notified of whether or not
+  // App Host installation was successful.
+  void AppHostInstaller::InstallAppHostIfNecessaryThenCall(

[erikwright (departed), 2012/10/05 02:21:56]

Remove the "ThenCall".

The presence of a callback in the signature, appropriately named and commented,
will be sufficient.

Rename 'final_step' to callback or completion_callback.

[huangs, 2012/10/05 19:46:08]

Done.

+      const Extension& extension,
+      const base::Callback<void(bool)>& final_step);
+
+ private:
+  // The implementation.
+  AppHostInstallerImpl* impl_;

[huangs, 2012/10/04 22:56:42]

Not using scoped_ptr for this, since AppHostInstallerImpl is hidden (in
particular, no destructor).

+  DISALLOW_COPY_AND_ASSIGN(AppHostInstaller);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_H_