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

chrome/browser/extensions/app_host_installer_win.h

Index: chrome/browser/extensions/app_host_installer_win.h
diff --git a/chrome/browser/extensions/app_host_installer_win.h b/chrome/browser/extensions/app_host_installer_win.h
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+// 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 "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/win/object_watcher.h"
+#include "base/win/scoped_handle.h"
+#include "chrome/browser/extensions/app_host_installer_win.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace extensions {
+
+class Extension;
+
+// Called on the original calling thread after InstallAppHostIfNecessary()
+// is complete.  A boolean flag is passed, which is false iff the installation
+// was required but failed.
+typedef base::Callback<void(bool)> OnAppHostInstallationCompleteCallback;
+
+// Determines if the App Host is installed and, if not, installs it.
+class AppHostInstaller {
+ public:
+  // 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, and is passed a boolean to
+  // indicate success or failure of installation.
+  // No timeout is used - thus |completion_callback| may be held for an
+  // arbitrarily long time, including past browser shutdown.
+  static void EnsureAppHostInstalled(
+      const OnAppHostInstallationCompleteCallback& completion_callback);
+
+ private:
+  // Constructs an AppHostInstaller, which will call |completion_callback|
+  // on the specified thread upon installation completion.
+  AppHostInstaller(
+      const OnAppHostInstallationCompleteCallback& completion_callback,
+      content::BrowserThread::ID caller_thread_id);
+
+  ~AppHostInstaller();
+
+  // Checks the system state on the FILE thread. Will call
+  // InstallAppHostOnFileThread() if App Host is not installed.
+  void EnsureAppHostInstalledInternal();
+
+  // Runs on the FILE thread. Installs App Host by asynchronously triggering
+  // App Host installation. Will call FinishOnCallerThread() upon completion
+  // (successful or otherwise).
+  void InstallAppHostOnFileThread();
+
+  // Passes |success| to |completion_callback| on the original caller thread.
+  // Deletes the AppHostInstaller.
+  void FinishOnCallerThread(bool success);
+
+  OnAppHostInstallationCompleteCallback completion_callback_;
+  content::BrowserThread::ID caller_thread_id_;
+  base::win::ScopedHandle process_;
+  scoped_ptr<base::win::ObjectWatcher::Delegate> delegate_;
+  base::win::ObjectWatcher watcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppHostInstaller);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_APP_HOST_INSTALLER_WIN_H_