Correct iOS build for latest Xcode beta.

ios/public/test/test_updatable_resource_provider.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/public/test/test_updatable_resource_provider.h"
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 
 #pragma mark - TestUpdatabeResourceDescriptor
@@ skipping 25 matching lines @@
 
 #pragma mark - TestUpdatableResource
 
 // Dummy UpdatableResourceDescriptorBridge implementation that simply loads data
 // from the specified plist file.
 @interface TestUpdatableResource : NSObject<UpdatableResourceBridge>
 @property(nonatomic, readonly) id<UpdatableResourceDescriptorBridge> descriptor;
 - (instancetype)initWithDelegate:(id<UpdatableResourceDelegate>)delegate
                            plist:(NSString*)resource_identifier
     NS_DESIGNATED_INITIALIZER;
+- (instancetype)init NS_UNAVAILABLE;
 @end
 
 @implementation TestUpdatableResource {
   base::scoped_nsprotocol<id<UpdatableResourceDelegate>> _delegate;
   base::scoped_nsprotocol<id<UpdatableResourceDescriptorBridge>> _descriptor;
 }
 
 - (instancetype)initWithDelegate:(id<UpdatableResourceDelegate>)delegate
                            plist:(NSString*)resourceIdentifier {
   if (self = [super init]) {
     _delegate.reset([delegate retain]);
     _descriptor.reset([[TestUpdatabeResourceDescriptor alloc] init]);
     DCHECK([resourceIdentifier hasSuffix:@".plist"])
         << "TestUpdatableResource supports only the plist format";
     [_descriptor setBundleResourcePath:resourceIdentifier];
   }
   return self;
 }
 
+- (instancetype)init {
+  NOTREACHED();
+  return nil;
+}
+
 - (id<UpdatableResourceDescriptorBridge>)descriptor {
   return _descriptor.get();
 }
 
 - (id<UpdatableResourceDelegate>)delegate {
   return _delegate;
 }
 
 - (NSDictionary*)resourceData {
   return [NSDictionary
@@ skipping 18 matching lines @@
     NSString* resource_identifier,
     id<UpdatableResourceDelegate> delegate) {
   NSString* path =
       [NSString stringWithFormat:@"%@/gm-config/ANY/%@",
                                  [[NSBundle mainBundle] resourcePath],
                                  resource_identifier];
   return [[TestUpdatableResource alloc] initWithDelegate:delegate plist:path];
 }
 
 }  // namespace ios