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;
+
+namespace app_host_installer {
+
+// App Host installation is necessary if

[erikwright (departed), 2012/10/09 19:24:48]

This level of detail is inappropriate for the declaration. Use a declarative
style, and stick to the details clients care about:

// Determines if the App Host is installed and, if not, installs it.

Other details can be moved to the implementation.

[huangs, 2012/10/09 21:09:15]

Done.

+//   (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();

[erikwright (departed), 2012/10/09 19:24:48]

private

[huangs, 2012/10/09 21:09:15]

Done.  Added two parameters.

+
+  // Implements AppHostInstaller::InstallAppHostIfNecessary().

[erikwright (departed), 2012/10/09 19:24:48]

// Asynchronously checks the system state and installs the App Host if not
present. |completion_callback| will be notified on the caller's thread when the
installation process completes. No timeout is used - thus |completion_callback|
may be held for an arbitrarily long time, including past browser shutdown.

[huangs, 2012/10/09 21:09:15]

Done.

+  void InstallAppHostIfNecessary(

[erikwright (departed), 2012/10/09 19:24:48]

static, and rename to EnsureAppHostInstalled, since we are now doing the
"IfNecessary" bit elsewhere.

[huangs, 2012/10/09 21:09:15]

Done.

+      const Extension& extension,
+      const base::Callback<void(bool)>& completion_callback);
+
+ private:
+  ~AppHostInstallerImpl();
+
+  // Moves to the FILE thread. Continues InstallAppHostIfNecessary().

[erikwright (departed), 2012/10/09 19:24:48]

// Checks the system state on the FILE thread. Will trigger "InstallAppHost" if
App Host is not installed.

[huangs, 2012/10/09 21:09:15]

Done.

+  void InstallAppHostIfNecessaryInternal();

[erikwright (departed), 2012/10/09 19:24:48]

Rename to "EnsureAppHostInstalledInternal"

[huangs, 2012/10/09 21:09:15]

Done.

+
+  // Runs on the FILE thread. Installs App Host.

[erikwright (departed), 2012/10/09 19:24:48]

// Asynchronously triggers the App Host installation. Will call "Finish" upon
completion (successful or otherwise).

[huangs, 2012/10/09 21:09:15]

Done.

+  void InstallAppHost();
+
+  // Moves to the caller thread, calls |completion_callback| with |success|.
+  void Finish(bool success);

[erikwright (departed), 2012/10/09 19:24:48]

// Passes |success| to |completion_callback| on the original caller thread.
Deletes the AppHostInstallerImpl.

[huangs, 2012/10/09 21:09:15]

Done.

+
+  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 app_host_installer
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_IMPL_WIN_H_