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

chrome/browser/extensions/app_host_installer.h

Index: chrome/browser/extensions/app_host_installer.h
diff --git a/chrome/browser/extensions/app_host_installer.h b/chrome/browser/extensions/app_host_installer.h
new file mode 100644
index 0000000000000000000000000000000000000000..94eee74c2d9456d7613f139a3a3bdb4b01c2de68
--- /dev/null
+++ b/chrome/browser/extensions/app_host_installer.h
@@ -0,0 +1,39 @@
+// 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 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.
+  void AppHostInstaller::InstallAppHostIfNecessary(
+      const Extension& extension,
+      const base::Callback<void(bool)>& completion_callback);
+
+ private:
+  // The implementation.
+  AppHostInstallerImpl* impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppHostInstaller);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_H_