If account doesn't own app, attempt to obtain FreeOnDemand license for it.

DepotDownloader/ContentDownloader.cs

@@ -369,9 +369,16 @@ namespace DepotDownloader
 
             if (!AccountHasAccess(appId))
             {
-                string contentName = GetAppOrDepotName(INVALID_DEPOT_ID, appId);
-                Console.WriteLine("App {0} ({1}) is not available from this account.", appId, contentName);
-                return;
+                if (steam3.RequestFreeAppLicense(appId))
+                {
+                    Console.WriteLine("Obtained FreeOnDemand license for app {0}", appId);
+                }
+                else
+                {
+                    string contentName = GetAppOrDepotName(INVALID_DEPOT_ID, appId);
+                    Console.WriteLine("App {0} ({1}) is not available from this account.", appId, contentName);
+                    return;
+                }
             }
 
             Console.WriteLine("Using app branch: '{0}'.", branch);

DepotDownloader/Steam3Session.cs

@@ -225,6 +225,23 @@ namespace DepotDownloader
             }, () => { return completed; });
         }
 
+        public bool RequestFreeAppLicense(uint appId)
+        {
+            bool success = false;
+            bool completed = false;
+            Action<SteamApps.FreeLicenseCallback> cbMethod = (resultInfo) =>//(packageInfo) =>
+            {
+                completed = true;
+                success = resultInfo.GrantedApps.Contains(appId);
+            };
+
+            WaitUntilCallback(() => {
+                callbacks.Subscribe(steamApps.RequestFreeLicense(appId), cbMethod);
+            }, () => { return completed; });
+
+            return success;
+        }
+
         public void RequestAppTicket(uint appId)
         {
             if (AppTickets.ContainsKey(appId) || bAborted)