[Cronet] Retain block passed to setRequestFilterBlock on iOS.

components/cronet/ios/Cronet.mm

 // 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.
 
 #import "components/cronet/ios/Cronet.h"
 
 #include <memory>
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ skipping 49 matching lines @@
 // net::HTTPProtocolHandlerDelegate for Cronet.
 class CronetHttpProtocolHandlerDelegate
     : public net::HTTPProtocolHandlerDelegate {
  public:
   CronetHttpProtocolHandlerDelegate(net::URLRequestContextGetter* getter,
                                     RequestFilterBlock filter)
       : getter_(getter), filter_(filter, base::scoped_policy::RETAIN) {}
 
   void SetRequestFilterBlock(RequestFilterBlock filter) {
     base::AutoLock auto_lock(lock_);
-    filter_.reset(filter);
+    filter_.reset(filter, base::scoped_policy::RETAIN);
   }
 
  private:
   // net::HTTPProtocolHandlerDelegate implementation:
   bool CanHandleRequest(NSURLRequest* request) override {
     base::AutoLock auto_lock(lock_);
     if (filter_) {
       RequestFilterBlock block = filter_.get();
       return block(request);
     }
@@ skipping 198 matching lines @@
       base::SysNSStringToUTF8(hostResolverRulesForTesting));
 }
 
 // This is a non-public dummy method that prevents the linker from stripping out
 // the otherwise non-referenced methods from 'bidirectional_stream.cc'.
 + (void)preventStrippingCronetBidirectionalStream {
   bidirectional_stream_create(NULL, 0, 0);
 }
 
 @end