Application group identifier should respect ios_app_bundle_id_prefix.

ios/chrome/common/app_group/app_group_constants.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 "ios/chrome/common/app_group/app_group_constants.h"
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #include "components/version_info/version_info.h"
 
 namespace {
-NSString* const kChromeAppGroupIdentifier = @"group.com.google.chrome";
+NSString* const kChromeAppGroupIdentifier =
+    @"group." IOS_BUNDLE_ID_PREFIX ".chrome";
 }
 
 namespace app_group {
 
 const char kChromeAppGroupXCallbackCommand[] = "app-group-command";
 
 const char kChromeAppGroupCommandPreference[] =
     "GroupApp.ChromeAppGroupCommand";
 
 const char kChromeAppGroupCommandTimePreference[] = "CommandTime";
@@ skipping 56 matching lines @@
 NSURL* ShareExtensionItemsFolder() {
   NSURL* groupURL = [[NSFileManager defaultManager]
       containerURLForSecurityApplicationGroupIdentifier:ApplicationGroup()];
   NSURL* readingListURL =
       [groupURL URLByAppendingPathComponent:@"ShareExtensionItems"
                                 isDirectory:YES];
   return readingListURL;
 }
 
 }  // namespace app_group