Make "source" a required argument of AppLaunchParams and fill in the argument in all call points.

extensions/common/api/app_runtime.idl

Index: extensions/common/api/app_runtime.idl
diff --git a/extensions/common/api/app_runtime.idl b/extensions/common/api/app_runtime.idl
index 163db41562d6db31fa68ac7bc8f11820e8fc81c0..f729347912464611ed81482b9f6bc636bada63da 100644
--- a/extensions/common/api/app_runtime.idl
+++ b/extensions/common/api/app_runtime.idl
@@ -25,10 +25,15 @@ namespace app.runtime {
     command_line,
     file_handler,
     url_handler,
-
     system_tray,
     about_page,
-    keyboard
+    keyboard,
+    extensions_page,
+    management_api,
+    ephemeral_app,
+    background,
+    kiosk,
+    chrome_internal
   };
 
   // Optional data for the launch. Either <code>items</code>, or