Do not try to load empty images

chrome/browser/notifications/notification_ui_manager_mac.mm

 // Copyright 2015 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.
 
 #include "chrome/browser/notifications/notification_ui_manager_mac.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/mac/foundation_util.h"
@@ skipping 103 matching lines @@
       notification.context_message().empty()
           ? base::SysUTF8ToNSString(notification.origin_url().spec())
           : base::SysUTF16ToNSString(notification.context_message());
   [toast setInformativeText:informativeText];
 
   // TODO(miguelg): Implement support for buttons
   toast.get().hasActionButton = NO;
 
   // Some functionality is only available in 10.9+ or requires private APIs
   // Icon
-  if ([toast respondsToSelector:@selector(_identityImage)]) {
+  if ([toast respondsToSelector:@selector(_identityImage)] &&
+      !notification.icon().IsEmpty()) {
     [toast setValue:notification.icon().ToNSImage() forKey:@"_identityImage"];
     [toast setValue:@NO forKey:@"_identityImageHasBorder"];
   }
 
   // Tag
   if ([toast respondsToSelector:@selector(setIdentifier:)] &&
       !notification.tag().empty()) {
     [toast setValue:base::SysUTF8ToNSString(notification.tag())
              forKey:@"identifier"];
   }
@@ skipping 133 matching lines @@
           -1 /* buttons not yet implemented */);
 }
 
 - (BOOL)userNotificationCenter:(NSUserNotificationCenter*)center
      shouldPresentNotification:(NSUserNotification*)nsNotification {
   // Always display notifications, regardless of whether the app is foreground.
   return YES;
 }
 
 @end