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

net/proxy/proxy_resolver_factory_mojo_unittest.cc

Index: net/proxy/proxy_resolver_factory_mojo_unittest.cc
diff --git a/net/proxy/proxy_resolver_factory_mojo_unittest.cc b/net/proxy/proxy_resolver_factory_mojo_unittest.cc
index da9ac3367e5a2aac2f5dc2ccff37693adc685b1b..e72f3e9e7b64da7217adc725a49eaf8788e61aac 100644
--- a/net/proxy/proxy_resolver_factory_mojo_unittest.cc
+++ b/net/proxy/proxy_resolver_factory_mojo_unittest.cc
@@ -476,7 +476,7 @@ class MockHostResolver : public HostResolver {
               RequestPriority priority,
               AddressList* addresses,
               const CompletionCallback& callback,
-              RequestHandle* request_handle,
+              std::unique_ptr<Request>* request_handle,
               const BoundNetLog& source_net_log) override {
     waiter_.NotifyEvent(DNS_REQUEST);
     return ERR_IO_PENDING;
@@ -486,7 +486,6 @@ class MockHostResolver : public HostResolver {
                        const BoundNetLog& source_net_log) override {
     return ERR_DNS_CACHE_MISS;
   }
-  void CancelRequest(RequestHandle req) override {}
   HostCache* GetHostCache() override { return nullptr; }
 
   EventWaiter<Event>& waiter() { return waiter_; }