Remove support for custom NSURLProtocol.

ios/chrome/app/startup/network_stack_setup.h

 // 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.
 
 #ifndef IOS_CHROME_APP_STARTUP_NETWORK_STACK_SETUP_H_
 #define IOS_CHROME_APP_STARTUP_NETWORK_STACK_SETUP_H_
 
 #import <UIKit/UIKit.h>
 
 #import <memory>
 
 namespace web {
 class RequestTrackerFactoryImpl;
-class WebHTTPProtocolHandlerDelegate;
 }  // namespace web
 
 @interface NetworkStackSetup : NSObject
 
 // Sets up the network stack: protocol handler and cache.
-// TODO(crbug.com/585700): Remove the first parameter.
-+ (void)setUpChromeNetworkStack:
-            (std::unique_ptr<web::RequestTrackerFactoryImpl>*)
-                requestTrackerFactory
-    httpProtocolHandlerDelegate:
-        (std::unique_ptr<web::WebHTTPProtocolHandlerDelegate>*)
-            httpProtocolHandlerDelegate;
+// TODO(crbug.com/585700): Remove the return value.
++ (std::unique_ptr<web::RequestTrackerFactoryImpl>)setUpChromeNetworkStack;
 
 @end
 
 #endif  // IOS_CHROME_APP_STARTUP_NETWORK_STACK_SETUP_H_