fixed file downloads for chrome app

app/js/lib/mtproto_wrapper.js

@@ -467,6 +467,14 @@ angular.module('izhukov.mtproto.wrapper', ['izhukov.utils', 'izhukov.mtproto'])
             writeFileDeferred;
         if (fileWriter.length) {
           startOffset = fileWriter.length;
+          if (startOffset >= size) {
+            if (toFileEntry) {
+              deferred.resolve(fileWriter.finalize());
+            } else {
+              deferred.resolve(cachedDownloads[fileName] = fileWriter.finalize());
+            }
+            return;
+          }
           fileWriter.seek(startOffset);
           deferred.notify({done: startOffset, total: size});
         }

app/js/services.js

@@ -2855,11 +2855,13 @@ angular.module('myApp.services', ['myApp.i18n', 'izhukov.utils'])
     });
 
     downloadPromise.then(function (blob) {
+      delete historyDoc.progress;
+      if (blob) {
         FileManager.getFileCorrectUrl(blob, doc.mime_type).then(function (url) {
           historyDoc.url = $sce.trustAsResourceUrl(url);
         })
-      delete historyDoc.progress;
         historyDoc.downloaded = true;
+      }
       console.log('file save done');
     }, function (e) {
       console.log('document download failed', e);