SdchManager: remove EnableSdchSupport

ios/crnet/crnet_environment.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.
 
 #include "ios/crnet/crnet_environment.h"
 
 #import <Foundation/Foundation.h>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
@@ skipping 310 matching lines @@
     // Set up an empty default cache, with default size.
     // TODO(droger): If the NSURLCache is to be used, its size should most
     // likely be changed. On an iPod2 with iOS4, the default size is 512k.
     [NSURLCache setSharedURLCache:[[[NSURLCache alloc] init] autorelease]];
     [NSURLProtocol unregisterClass:[CRNPauseableHTTPProtocolHandler class]];
   }
 }
 
 void CrNetEnvironment::ConfigureSdchOnNetworkThread() {
   DCHECK(base::MessageLoop::current() == network_io_thread_->message_loop());
+  net::URLRequestContext* context =
+      main_context_getter_->GetURLRequestContext();
 
   if (!sdch_enabled_) {
-    net::SdchManager::EnableSdchSupport(false);
+    DCHECK_EQ(static_cast<net::SdchManager*>(nullptr), context->sdch_manager());
     return;
   }
 
   sdch_manager_.reset(new net::SdchManager());
-  net::URLRequestContext* context =
-      main_context_getter_->GetURLRequestContext();
   sdch_owner_.reset(new net::SdchOwner(sdch_manager_.get(), context));
   if (!sdch_pref_store_filename_.empty()) {
     base::FilePath path(sdch_pref_store_filename_);
     pref_store_worker_pool_ = file_user_blocking_thread_->task_runner();
     net_pref_store_ = new JsonPrefStore(
         path,
         pref_store_worker_pool_.get(),
         scoped_ptr<PrefFilter>());
     net_pref_store_->ReadPrefsAsync(nullptr);
     sdch_owner_->EnablePersistentStorage(net_pref_store_.get());
@@ skipping 144 matching lines @@
       if (backend)
         backend->DoomAllEntries(client_callback);
   });
   int rc = cache->GetBackend(&backend, doom_callback);
   if (rc != net::ERR_IO_PENDING) {
     // GetBackend doesn't call the callback if it completes synchronously, so
     // call it directly here.
     doom_callback.Run(rc);
   }
 }