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

chrome/browser/extensions/app_host_installer_impl_win.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_IMPL_WIN_H_
+#define CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_IMPL_WIN_H_
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/win/object_watcher.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace extensions {
+
+class Extension;
+
+// App Host installation is necessary if
+//   (1) |extension| is platform app, and
+//   (2) app_host_exe is not installed.
+// (1) can be checked anywhere, but (2) must be checked in the FILE thread.
+// App Host installation is also launched in the FILE thread as an
+// asynchronous process.  Once installation completes, QuickEnableWatcher
+// is notified (on the FILE thread). This in turn notifies the caller thread
+// which then proceed with the next step specified by |completion_callback|,
+// on the caller thread.
+class AppHostInstallerImpl {
+ public:
+  AppHostInstallerImpl();
+
+  // Implements AppHostInstaller::InstallAppHostIfNecessary().
+  void InstallAppHostIfNecessary(
+      const Extension& extension,
+      const base::Callback<void(bool)>& completion_callback);
+
+ private:
+  // Moves to the FILE thread. Continues InstallAppHostIfNecessary().
+  void InstallAppHostIfNecessaryInternal();
+
+  // Runs on the FILE thread. Installs App Host.
+  void InstallAppHost();
+
+  // Moves to the caller thread, calls |completion_callback| with |success|.
+  void Finish(bool success);
+
+  base::win::ScopedHandle process_;
+  base::win::ObjectWatcher watcher_;
+  scoped_ptr<base::win::ObjectWatcher::Delegate> delegate_;
+  content::BrowserThread::ID caller_thread_id_;
+  base::Callback<void(bool)> completion_callback_;
+
+ DISALLOW_COPY_AND_ASSIGN(AppHostInstallerImpl);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_IMPL_WIN_H_