CrNet: add pauseable NSURLProtocol and switch to using it

ios/crnet/crnet_consumer/main.m

Index: ios/crnet/crnet_consumer/main.m
diff --git a/ios/crnet/crnet_consumer/main.m b/ios/crnet/crnet_consumer/main.m
deleted file mode 100644
index 0a3e5f482182645d63278148bac4df7aee5a480b..0000000000000000000000000000000000000000
--- a/ios/crnet/crnet_consumer/main.m
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2014 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 <Foundation/Foundation.h>
-#import <UIKit/UIKit.h>
-
-#import "crnet_consumer_app_delegate.h"
-
-int main(int argc, char *argv[]) {
-  @autoreleasepool {
-    return UIApplicationMain(
-        argc, argv, nil, NSStringFromClass([CrNetConsumerAppDelegate class]));
-  }
-}