Revert of Remove support for Alt-Svc/Alternate Protocol Probability

ios/crnet/crnet_consumer/crnet_consumer_app_delegate.mm

 // 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 "crnet_consumer_app_delegate.h"
 
 #import "CrNet.h"
 #include "base/format_macros.h"
 #import "crnet_consumer_view_controller.h"
 
@@ skipping 27 matching lines @@
       withIntermediateDirectories:YES
                        attributes:nil
                             error:&error];
   return error != nil ? [prefStoreFile path] : nil;
 }
 
 - (BOOL)application:(UIApplication*)application
     didFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
   [CrNet setPartialUserAgent:@"Dummy/1.0"];
   [CrNet setQuicEnabled:YES];
+  // Always use QUIC if able.
+  [CrNet setAlternateProtocolThreshold:0.0];
   [CrNet setSDCHEnabled:YES withPrefStore:[self SDCHPrefStoreFileName]];
   [CrNet install];
   [CrNet startNetLogToFile:[self currentNetLogFileName] logBytes:NO];
 
   NSURLSessionConfiguration* config =
       [NSURLSessionConfiguration ephemeralSessionConfiguration];
   [CrNet installIntoSessionConfiguration:config];
 
   // Just for fun, don't route chromium.org requests through CrNet.
   //
@@ skipping 22 matching lines @@
     NSLog(@"Cache cleared: %d\n", error);
   }];
 }
 
 - (void)applicationWillEnterForeground:(UIApplication*)application {
   _counter++;
   [CrNet startNetLogToFile:[self currentNetLogFileName] logBytes:NO];
 }
 
 @end