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

chrome/browser/extensions/crx_installer.h

Index: chrome/browser/extensions/crx_installer.h
diff --git a/chrome/browser/extensions/crx_installer.h b/chrome/browser/extensions/crx_installer.h
index e9541dec8204defc135dbc6dfef30595eab22ef2..bf0aba9e615ba52b59b9141b83e9565391f832c2 100644
--- a/chrome/browser/extensions/crx_installer.h
+++ b/chrome/browser/extensions/crx_installer.h
@@ -12,6 +12,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/version.h"
+#include "chrome/browser/extensions/app_host_installer.h"
 #include "chrome/browser/extensions/crx_installer_error.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 #include "chrome/browser/extensions/sandboxed_unpacker.h"
@@ -214,8 +215,15 @@ class CrxInstaller
   // 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 Host is installed, and then
+  // proceeds to post CompleteExtensionInstall().
+  void BeginInstall();
+
+  // Callback founction for AppHostInstaller.
+  void OnAppHostInstallation(bool success);
+
+  // Runs on File thread. Installs the unpacked extension into the profile and
+  // notifies the frontend.
   void CompleteInstall();
 
   // Result reporting.
@@ -359,6 +367,9 @@ class CrxInstaller
 
   bool has_requirement_errors_;
 
+  // Helper to install App Host.
+  AppHostInstaller app_host_installer_;
+
   DISALLOW_COPY_AND_ASSIGN(CrxInstaller);
 };