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

chrome/browser/extensions/app_host_installer_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_WIN_H_
+#define CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_WIN_H_
+
+#include <windows.h>
+#include "base/bind.h"
+#include "base/win/object_watcher.h"
+#include "base/win/scoped_handle.h"
+
+namespace extensions {
+
+class AppHostInstaller {
+ public:
+  AppHostInstaller();
+  void EnsureAppHostPresentAndCall(const base::Closure& on_success,

[benwells, 2012/10/03 05:08:43]

Please add a comment explaining that this can only be run on the FILE thread.

Also, I think it might be better to have something like:
bool IsAppHostInstallRequired(Extension*)

as well as
void InstallAppHost(...);

Usage would be:

  .......
  if (IsAppHostInstallRequired(extension)) {
    InstallAppHost(callbacks);
    return;
  }

  CompleteIt();
}

That way the common case of not needing to install has a nice simple flow in the
program.

Whether you have two closures or one callback with a bool parameter indicating
success is probably a matter of opinion; I would go with one.

[erikwright (departed), 2012/10/03 15:58:35]

Sure, a static IsAppHostRequired(Extension*) seems a good idea.

[huangs, 2012/10/03 20:09:47]

Done, but added another function OnAppHostInstallation(bool)  as callback.

[huangs, 2012/10/03 20:09:47]

Done (Made static).

+      const base::Closure& on_failure);
+
+ private:
+  bool running_;
+  base::win::ScopedHandle process_;
+  base::win::ObjectWatcher watcher_;
+  scoped_ptr<base::win::ObjectWatcher::Delegate> delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppHostInstaller);
+};
+
+}  // namespace extensions
+
+
+#endif  // CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_WIN_H_