Add a flag that lets the webstore show a different UI on app install.

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 171105b340e01e473a47fabbb1f02a5c14b079fa..1db81048c31b0987d3ef49292d257b2a8fb058ad 100644
--- a/chrome/browser/extensions/crx_installer.h
+++ b/chrome/browser/extensions/crx_installer.h
@@ -61,6 +61,10 @@ class CrxInstaller
 
     scoped_ptr<base::DictionaryValue> parsed_manifest;
     std::string localized_name;
+
+    // Whether to use a bubble notification when an app is installed, instead of
+    // the default behavior of transitioning to the new tab page.
+    bool use_app_installed_bubble;
   };
 
   // Exempt the next extension install with |id| from displaying a confirmation