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

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
old mode 100644
new mode 100755
index d4e401c23be100ab9ca33d31595ac4ebe2aa5857..3f7d5f73014bc51d6f372b543f62fa8c2530b0b8
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -5083,6 +5083,9 @@ Public Exponent (<ph name="PUBLIC_EXPONENT_NUM_BITS">$3<ex>24</ex></ph> bits):
       <message name="IDS_EXTENSION_PACKAGE_IMAGE_ERROR" desc="Message for when an error occurs while trying to decode an image found within a packaged extension or app.">
         Could not decode image: '<ph name="IMAGE_NAME">$1<ex>image.png</ex></ph>'
       </message>
+      <message name="IDS_EXTENSION_APP_HOST_INSTALL_ERROR" desc="Message for when an App Host fails to install.">
+        Application Runtime installation failed.
+      </message>
 
       <!-- Extension installed bubble -->
       <message name="IDS_EXTENSION_BUNDLE_INSTALLED_HEADING_EXTENSIONS" desc="First line in the content area of the extension bundle installed bubble. Instructs which extensions were installed.">