Domain Reliability: Don't crash on shutdown with uploads pending

components/domain_reliability/monitor_unittest.cc

Index: components/domain_reliability/monitor_unittest.cc
diff --git a/components/domain_reliability/monitor_unittest.cc b/components/domain_reliability/monitor_unittest.cc
index 8fc589a327c12665efe496818d80354dc048f61e..2e46fda2aec47cda6d7ae2693e5a162849e8fb57 100644
--- a/components/domain_reliability/monitor_unittest.cc
+++ b/components/domain_reliability/monitor_unittest.cc
@@ -68,6 +68,10 @@ class DomainReliabilityMonitorTest : public testing::Test {
     monitor_.SetDiscardUploads(false);
   }
 
+  ~DomainReliabilityMonitorTest() override {
+    monitor_.Shutdown();
+  }
+
   static RequestInfo MakeRequestInfo() {
     RequestInfo request;
     request.status = net::URLRequestStatus();