Correct iOS build for latest Xcode beta.

ios/web/crw_browsing_data_store.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.
 
 #import "ios/web/public/crw_browsing_data_store.h"
 
 #import <Foundation/Foundation.h>
 
 #include "base/ios/ios_util.h"
 #import "base/ios/weak_nsobject.h"
@@ skipping 27 matching lines @@
 
 @interface CRWBrowsingDataStore ()
 // Returns a serial queue on which stash and restore operations can be scheduled
 // to be run. All stash/restore operations need to be run on the same queue
 // hence it is shared with all CRWBrowsingDataStores.
 + (NSOperationQueue*)operationQueueForStashAndRestoreOperations;
 // Returns a concurrent queue on which remove operations can be scheduled to be
 // run. All remove operations need to be run on the same queue hence it is
 // shared with all CRWBrowsingDataStores.
 + (NSOperationQueue*)operationQueueForRemoveOperations;
+- (instancetype)init NS_UNAVAILABLE;
 
 // The array of all browsing data managers. Must be accessed from the main
 // thread.
 @property(nonatomic, readonly) NSArray* allBrowsingDataManagers;
 // Returns an array of browsing data managers for the given |browsingDataTypes|.
 - (NSArray*)browsingDataManagersForBrowsingDataTypes:
         (web::BrowsingDataTypes)browsingDataTypes;
 // Returns the selector that needs to be performed on the
 // CRWBrowsingDataManagers for the |operationType|. |operationType| cannot be
 // |NONE|.
@@ skipping 111 matching lines @@
     base::scoped_nsobject<CRWCookieBrowsingDataManager>
         cookieBrowsingDataManager([[CRWCookieBrowsingDataManager alloc]
             initWithBrowserState:browserState]);
     _browsingDataTypeMap.reset([@{
       @(web::BROWSING_DATA_TYPE_COOKIES) : cookieBrowsingDataManager,
     } retain]);
   }
   return self;
 }
 
+- (instancetype)init {
+  NOTREACHED();
+  return nil;
+}
+
 - (NSString*)description {
   NSString* format = @"<%@: %p; hasPendingOperations = { %@ }>";
   NSString* hasPendingOperationsString =
       [self hasPendingOperations] ? @"YES" : @"NO";
   NSString* result =
       [NSString stringWithFormat:format, NSStringFromClass(self.class), self,
                                  hasPendingOperationsString];
   return result;
 }
 
@@ skipping 275 matching lines @@
   DCHECK(queue);
 
   if (_lastDispatchedOperation) {
     [operation addDependency:_lastDispatchedOperation];
   }
   _lastDispatchedOperation.reset([operation retain]);
   [queue addOperation:operation];
 }
 
 @end