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

chrome/browser/extensions/unpacked_installer.h

Index: chrome/browser/extensions/unpacked_installer.h
diff --git a/chrome/browser/extensions/unpacked_installer.h b/chrome/browser/extensions/unpacked_installer.h
index 6b48857aecdb039279a992d392c49f8c72063755..6956281680fa55ab7f19b12642647a75e5aa28b6 100644
--- a/chrome/browser/extensions/unpacked_installer.h
+++ b/chrome/browser/extensions/unpacked_installer.h
@@ -70,11 +70,11 @@ class UnpackedInstaller
   // Verifies if loading unpacked extensions is allowed.
   bool IsLoadingUnpackedAllowed() const;
 
-  // We change the input extension path to an absolute path, on the file thread.
+  // We change the input extension path to an absolute path, on the FILE thread.
   // Then we need to check the file access preference, which needs
   // to happen back on the UI thread, so it posts CheckExtensionFileAccess on
   // the UI thread. In turn, once that gets the pref, it goes back to the
-  // file thread with LoadWithFileAccess.
+  // FILE thread with LoadWithFileAccess.
   // TODO(yoz): It would be nice to remove this ping-pong, but we need to know
   // what file access flags to pass to extension_file_util::LoadExtension.
   void GetAbsolutePath();
@@ -87,6 +87,19 @@ class UnpackedInstaller
   // Called when an unpacked extension has been loaded and installed.
   void OnLoaded();
 
+  // Runs on UI thread. If App Host is not installed, calls installer and
+  // posts OnAppHostInstallationComplete() as call back.  Else proceeds to
+  // CompleteInstall().
+  void BeginInstall();
+
+  // Runs on UI thread. Callback function for AppHostInstaller.
+  // If not |success|, shows error message. Else proceeds to CompleteInstall().
+  void OnAppHostInstallation(bool success);
+
+  // Runs on UI thread. Installs the unpacked extension into the profile and
+  // notifies the frontend.
+  void CompleteInstall();
+
   // Helper to get the Extension::CreateFlags for the installing extension.
   int GetFlags();