Disable Share extension item receiver if there is no app group.

ios/chrome/browser/share_extension/share_extension_item_receiver.mm

 // 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 "ios/chrome/browser/share_extension/share_extension_item_receiver.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/ios/block_types.h"
 #include "base/mac/bind_objc_block.h"
@@ skipping 80 matching lines @@
       [[ShareExtensionItemReceiver alloc] init];
   return instance;
 }
 
 - (void)setBookmarkModel:(bookmarks::BookmarkModel*)bookmarkModel
         readingListModel:(ReadingListModel*)readingListModel {
   DCHECK_CURRENTLY_ON(web::WebThread::UI);
   DCHECK(!_readingListModel);
   DCHECK(!_bookmarkModel);
 
-#if TARGET_IPHONE_SIMULATOR

[rohitrao (ping after 24h), 2016/12/19 09:40:33]

We're running egtests on devices as well, that's where I first noticed the
issue.  I'm not sure I've ever actually seen this crash on simulator.

Will this change cause any tests to fail, since we're effectively turning off
functionality?

Should we add the entitlement to egtests instead?

[sdefresne, 2016/12/20 01:03:38]

I think we should try to get the entitlements for egtests, but it needs some
work. For the moment, I think it is fine just turning this off.

   if (![self presentedItemURL]) {
     return;
   }
-#else
-  DCHECK([self presentedItemURL]);
-#endif
 
   _readingListModel = readingListModel;
   _bookmarkModel = bookmarkModel;
 
   web::WebThread::PostTask(web::WebThread::FILE, FROM_HERE,
                            base::BindBlockArc(^() {
                              [self createReadingListFolder];
                            }));
   [[NSNotificationCenter defaultCenter]
       addObserver:self
@@ skipping 228 matching lines @@
 
 - (NSOperationQueue*)presentedItemOperationQueue {
   return [NSOperationQueue mainQueue];
 }
 
 - (NSURL*)presentedItemURL {
   return app_group::ShareExtensionItemsFolder();
 }
 
 @end