Change HostResolver::Resolve() to take an std::unique_ptr<Request>* rather than a RequestHandle*

net/dns/host_resolver_mojo.h

 // Copyright 2015 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.
 
 #ifndef NET_DNS_HOST_RESOLVER_MOJO_H_
 #define NET_DNS_HOST_RESOLVER_MOJO_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
@@ skipping 19 matching lines @@
   // |impl| must outlive |this|.
   explicit HostResolverMojo(Impl* impl);
   ~HostResolverMojo() override;
 
   // HostResolver overrides.
   // Note: |Resolve()| currently ignores |priority|.
   int Resolve(const RequestInfo& info,
               RequestPriority priority,
               AddressList* addresses,
               const CompletionCallback& callback,
-              RequestHandle* request_handle,
+              std::unique_ptr<Request>* request,
               const BoundNetLog& source_net_log) override;
   int ResolveFromCache(const RequestInfo& info,
                        AddressList* addresses,
                        const BoundNetLog& source_net_log) override;
-  void ChangeRequestPriority(RequestHandle req,
-                             RequestPriority priority) override;
-  void CancelRequest(RequestHandle req) override;
   HostCache* GetHostCache() override;
 
  private:
   class Job;
+  class RequestImpl;
 
   int ResolveFromCacheInternal(const RequestInfo& info,
                                const HostCache::Key& key,
                                AddressList* addresses);
 
   Impl* const impl_;
 
   std::unique_ptr<HostCache> host_cache_;
   base::WeakPtrFactory<HostCache> host_cache_weak_factory_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverMojo);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_HOST_RESOLVER_MOJO_H_