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

chrome/browser/extensions/app_host_installer.cc

Index: chrome/browser/extensions/app_host_installer.cc
diff --git a/chrome/browser/extensions/app_host_installer.cc b/chrome/browser/extensions/app_host_installer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1130987af143c513946d456061391770bca865e5
--- /dev/null
+++ b/chrome/browser/extensions/app_host_installer.cc
@@ -0,0 +1,32 @@
+// 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.
+
+#include "chrome/browser/extensions/app_host_installer.h"
+#include "chrome/common/extensions/extension.h"
+
+#include "base/callback.h"
+
+#if defined(OS_WIN)
+#include "chrome/browser/extensions/app_host_installer_impl_win.h"
+#endif
+
+namespace extensions {
+
+namespace app_host_installer {
+
+void InstallAppHostIfNecessary(const Extension& extension,
+    const base::Callback<void(bool)>& completion_callback) {
+#if defined(OS_WIN)
+  if (extension.is_platform_app())
+    AppHostInstallerImpl::EnsureAppHostInstalled(completion_callback);
+  else
+    completion_callback.Run(true);
+#else
+  completion_callback.Run(true);
+#endif
+}
+
+}  // namespace app_host_installer
+
+}  // namespace extensions