Added unpacking step

chrome/installer/mac/app/InstallerWindowController.m

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "InstallerWindowController.h"
 
 #import "AppDelegate.h"
 
 @interface InstallerWindowController () {
   NSButton* importButton_;
@@ skipping 93 matching lines @@
 - (void)updateStatusDescription:(NSString*)text {
   // First setStringValue statement is required to clear the original string.
   // Omitting the first line will cause occasional ghosting of the previous
   // string.
   // TODO: Find a real solution to the ghosting problem.
   //  downloadProgressDescription_.stringValue = @"";
   downloadProgressDescription_.stringValue = text;
 }
 
 - (void)updateDownloadProgress:(double)progressPercent {
-  progressBar_.doubleValue = progressPercent;
+  if (progressPercent > 0.0) {
+    progressBar_.doubleValue = progressPercent;
+  } else {
+    progressBar_.doubleValue = 0.0;
+    progressBar_.indeterminate = YES;
+    [progressBar_ startAnimation:nil];
+  }
 }
 
 @end