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

net/dns/single_request_host_resolver_unittest.cc

Index: net/dns/single_request_host_resolver_unittest.cc
diff --git a/net/dns/single_request_host_resolver_unittest.cc b/net/dns/single_request_host_resolver_unittest.cc
index c0b3a7b82cda8a8c031580ad4adb3b85d4bbfb58..acbac190392d5e12f7cd1add31257b6ee9e31b99 100644
--- a/net/dns/single_request_host_resolver_unittest.cc
+++ b/net/dns/single_request_host_resolver_unittest.cc
@@ -20,7 +20,6 @@ using net::test::IsOk;
 namespace net {
 
 namespace {
-
 // Helper class used by SingleRequestHostResolverTest.Cancel test.
 // It checks that only one request is outstanding at a time, and that
 // it is cancelled before the class is destroyed.
@@ -38,11 +37,11 @@ class HangingHostResolver : public HostResolver {
               RequestPriority priority,
               AddressList* addresses,
               const CompletionCallback& callback,
-              RequestHandle* out_req,
+              std::unique_ptr<Request>* out_req,
               const BoundNetLog& net_log) override {
     EXPECT_FALSE(has_outstanding_request());
-    outstanding_request_ = reinterpret_cast<RequestHandle>(0x1234);
-    *out_req = outstanding_request_;
+    outstanding_request_ = new RequestImpl(this);
+    (*out_req).reset(outstanding_request_);
 
     // Never complete this request! Caller is expected to cancel it
     // before destroying the resolver.
@@ -56,14 +55,32 @@ class HangingHostResolver : public HostResolver {
     return ERR_UNEXPECTED;
   }
 
-  void CancelRequest(RequestHandle req) override {
-    EXPECT_TRUE(has_outstanding_request());
-    EXPECT_EQ(req, outstanding_request_);
-    outstanding_request_ = NULL;
-  }
-
  private:
-  RequestHandle outstanding_request_;
+  class RequestImpl : public HostResolver::Request {
+   public:
+    RequestImpl(HangingHostResolver* resolver) : resolver_(resolver) {}
+
+    ~RequestImpl() override {
+      if (resolver_) {
+        EXPECT_TRUE(resolver_->has_outstanding_request());
+        EXPECT_EQ(resolver_->outstanding_request_, this);
+        resolver_->outstanding_request_ = nullptr;
+      }
+    }
+
+    void ChangeRequestPriority(RequestPriority priority) override {}
+
+    void RemoveResolver() { resolver_ = nullptr; }
+
+   private:
+    HangingHostResolver* resolver_;
+
+    DISALLOW_COPY_AND_ASSIGN(RequestImpl);
+  };
+
+  friend RequestImpl;
+
+  RequestImpl* outstanding_request_;
 
   DISALLOW_COPY_AND_ASSIGN(HangingHostResolver);
 };