Bug 1549386 - Turn nsIPageThumbsStorageService.path into AString. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D33983

--HG--
extra : moz-landing-system : lando

toolkit/components/thumbnails/nsIPageThumbsStorageService.idl

@@ -21,7 +21,7 @@ interface nsIPageThumbsStorageService : nsISupports
   /**
    * Returns the path where the thumbnails are stored
    */
-  readonly attribute ACString path;
+  readonly attribute AString path;
 
   /**
    * Returns the full file path containing the screenshot for a given URL