Correct iOS build for latest Xcode beta.

ios/chrome/browser/xcallback_parameters.mm

 // Copyright 2012 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/xcallback_parameters.h"
 
+#include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 
 namespace {
 NSString* const kSourceAppIdKey = @"sourceAppId";
 NSString* const kSourceAppNameKey = @"sourceAppName";
 NSString* const kSuccessURLKey = @"successURL";
 NSString* const kCreateNewTabKey = @"createNewTab";
 }
 
 @interface XCallbackParameters () {
   base::scoped_nsobject<NSString> _sourceAppId;
   base::scoped_nsobject<NSString> _sourceAppName;
   GURL _successURL;
   BOOL _createNewTab;
 }
 @end
 
 @implementation XCallbackParameters
 
 @synthesize successURL = _successURL;
 @synthesize createNewTab = _createNewTab;
 
+- (instancetype)init {
+  NOTREACHED();
+  return nil;
+}
+
 - (instancetype)initWithSourceAppId:(NSString*)sourceAppId
                       sourceAppName:(NSString*)sourceAppName
                          successURL:(const GURL&)successURL
                        createNewTab:(BOOL)createNewTab {
   self = [super init];
   if (self) {
     _sourceAppId.reset([sourceAppId copy]);
     _sourceAppName.reset([sourceAppName copy]);
     _successURL = successURL;
     _createNewTab = createNewTab;
@@ skipping 45 matching lines @@
 - (instancetype)copyWithZone:(NSZone*)zone {
   XCallbackParameters* copy = [[[self class] allocWithZone:zone] init];
   copy->_sourceAppId.reset([_sourceAppId copy]);
   copy->_sourceAppName.reset([_sourceAppName copy]);
   copy->_successURL = _successURL;
   copy->_createNewTab = _createNewTab;
   return copy;
 }
 
 @end