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

chrome/browser/extensions/crx_installer.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_CRX_INSTALLER_H_
 #define CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 13 matching lines @@
 class SkBitmap;
 
 namespace extensions {
 class ExtensionUpdaterTest;
 class RequirementsChecker;
 
 // This class installs a crx file into a profile.
 //
 // Installing a CRX is a multi-step process, including unpacking the crx,
 // validating it, prompting the user, and installing. Since many of these
-// steps must occur on the file thread, this class contains a copy of all data
+// steps must occur on the FILE thread, this class contains a copy of all data
 // necessary to do its job. (This also minimizes external dependencies for
 // easier testing).
 //
 // Lifetime management:
 //
 // This class is ref-counted by each call it makes to itself on another thread,
 // and by UtilityProcessHost.
 //
 // Additionally, we hold a reference to our own client so that it lives at least
 // long enough to receive the result of unpacking.
@@ skipping 168 matching lines @@
   // Called on the UI thread to start the requirements check on the extension.
   void CheckRequirements();
 
   // Runs on the UI thread. Callback from RequirementsChecker.
   void OnRequirementsChecked(std::vector<std::string> requirement_errors);
 
   // Runs on the UI thread. Confirms with the user (via ExtensionInstallPrompt)
   // that it is OK to install this extension.
   void ConfirmInstall();
 
-  // Runs on File thread. Install the unpacked extension into the profile and
-  // notify the frontend.
+  // Runs on FILE thread. Ensures that app is not downgraded. If App Host is
+  // not installed, calls installer and posts OnAppHostInstallationComplete()
+  // as call back.  Else proceeds to CompleteInstall().
+  void BeginInstall();
+
+  // Runs on FILE thread. Callback function for AppHostInstaller.
+  // If not |success|, shows error message. Else proceeds to CompleteInstall().
+  void OnAppHostInstallationComplete(bool success);
+
+  // Runs on FILE thread. Installs the unpacked extension into the profile and
+  // notifies the frontend.
   void CompleteInstall();
 
   // Result reporting.
   void ReportFailureFromFileThread(const CrxInstallerError& error);
   void ReportFailureFromUIThread(const CrxInstallerError& error);
   void ReportSuccessFromFileThread();
   void ReportSuccessFromUIThread();
   void NotifyCrxInstallComplete(const Extension* extension);
 
   // The file we're installing.
@@ skipping 70 matching lines @@
   FilePath temp_dir_;
 
   // The frontend we will report results back to.
   base::WeakPtr<ExtensionService> frontend_weak_;
 
   // The Profile where the extension is being installed in.
   Profile* profile_;
 
   // The client we will work with to do the installation. This can be NULL, in
   // which case the install is silent.
-  // NOTE: we may be deleted on the file thread. To ensure the UI is deleted on
+  // NOTE: we may be deleted on the FILE thread. To ensure the UI is deleted on
   // the main thread we don't use a scoped_ptr here.
   ExtensionInstallPrompt* client_;
 
   // The root of the unpacked extension directory. This is a subdirectory of
   // temp_dir_, so we don't have to delete it explicitly.
   FilePath unpacked_extension_root_;
 
   // True when the CRX being installed was just downloaded.
   // Used to trigger extra checks before installing.
   bool apps_require_extension_mime_type_;
@@ skipping 41 matching lines @@
 
   // Used to show the install dialog.
   ExtensionInstallPrompt::ShowDialogCallback show_dialog_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(CrxInstaller);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_