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

ios/crnet/CrNet.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 "ios/crnet/CrNet.h"
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/net/crn_http_protocol_handler.h"
 #import "ios/crnet/crnet_environment.h"
 
 static CrNetEnvironment* g_chrome_net = NULL;
 
 static BOOL g_spdy_enabled = YES;
 static BOOL g_quic_enabled = NO;
 static BOOL g_sdch_enabled = NO;
 static NSString* g_user_agent = nil;
 static NSString* g_sdch_pref_store_filename = nil;
+static double g_alternate_protocol_threshold = 1.0;
 static RequestFilterBlock g_request_filter_block = nil;
 
 @implementation CrNet
 
 + (void)setSpdyEnabled:(BOOL)spdyEnabled {
   g_spdy_enabled = spdyEnabled;
 }
 
 + (void)setQuicEnabled:(BOOL)quicEnabled {
   g_quic_enabled = quicEnabled;
 }
 
 + (void)setSDCHEnabled:(BOOL)sdchEnabled
          withPrefStore:(NSString*)filename {
   g_sdch_enabled = sdchEnabled;
   g_sdch_pref_store_filename = filename;
 }
 
 + (void)setPartialUserAgent:(NSString *)userAgent {
   g_user_agent = userAgent;
 }
 
++ (void)setAlternateProtocolThreshold:(double)alternateProtocolThreshold {
+  g_alternate_protocol_threshold = alternateProtocolThreshold;
+}
+
 + (void)installInternal {
   CrNetEnvironment::Initialize();
   std::string partial_user_agent = base::SysNSStringToUTF8(g_user_agent);
   g_chrome_net = new CrNetEnvironment(partial_user_agent);
 
   g_chrome_net->set_spdy_enabled(g_spdy_enabled);
   g_chrome_net->set_quic_enabled(g_quic_enabled);
   g_chrome_net->set_sdch_enabled(g_sdch_enabled);
   if (g_sdch_pref_store_filename) {
     std::string filename = base::SysNSStringToUTF8(g_sdch_pref_store_filename);
     g_chrome_net->set_sdch_pref_store_filename(filename);
   }
+  g_chrome_net->set_alternate_protocol_threshold(
+      g_alternate_protocol_threshold);
 
   g_chrome_net->Install();
   g_chrome_net->SetHTTPProtocolHandlerRegistered(true);
   g_chrome_net->SetRequestFilterBlock(g_request_filter_block);
 }
 
 + (void)install {
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
       [self installInternal];
@@ skipping 66 matching lines @@
   }
 }
 
 + (void)clearCacheWithCompletionCallback:(ClearCacheCallback)clearCacheCallback {
   if (g_chrome_net) {
     g_chrome_net->ClearCache(clearCacheCallback);
   }
 }
 
 @end