EDK: Add Core::DuplicateHandleWithReducedRights().

mojo/edk/system/dispatcher_unittest.cc

Index: mojo/edk/system/dispatcher_unittest.cc
diff --git a/mojo/edk/system/dispatcher_unittest.cc b/mojo/edk/system/dispatcher_unittest.cc
index dcbc999256f0e3787961b843761fd5cc723e435b..033c1601947f8c6929114b79411636c4d8fc37b8 100644
--- a/mojo/edk/system/dispatcher_unittest.cc
+++ b/mojo/edk/system/dispatcher_unittest.cc
@@ -141,6 +141,7 @@ TEST(DispatcherTest, Basic) {
 
 enum class DispatcherOp {
   CLOSE = 0,
+  DUPLICATE_DISPATCHER,
   WRITE_MESSAGE,
   READ_MESSAGE,
   SET_DATA_PIPE_PRODUCER_OPTIONS,
@@ -178,6 +179,18 @@ void ThreadSafetyStressHelper(ManualResetWaitableEvent* event,
           << "Result: " << r;
       break;
     }
+    case DispatcherOp::DUPLICATE_DISPATCHER: {
+      RefPtr<Dispatcher> new_dispatcher;
+      MojoResult r = dispatcher->DuplicateDispatcher(&new_dispatcher);
+      if (r == MOJO_RESULT_OK) {
+        EXPECT_TRUE(new_dispatcher);
+        EXPECT_EQ(MOJO_RESULT_OK, new_dispatcher->Close());
+      } else {
+        EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT, r);
+        EXPECT_FALSE(new_dispatcher);
+      }
+      break;
+    }
     case DispatcherOp::WRITE_MESSAGE:
       EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
                 dispatcher->WriteMessage(NullUserPointer(), 0, nullptr,