Fix crash in DirectoryImpl::Flush()

components/filesystem/directory_impl_unittest.cc

Index: components/filesystem/directory_impl_unittest.cc
diff --git a/components/filesystem/directory_impl_unittest.cc b/components/filesystem/directory_impl_unittest.cc
index 250c6de2e1932906034ffc5413389409705f98ab..771749704782693554407a40b3417d8f1ae6a204 100644
--- a/components/filesystem/directory_impl_unittest.cc
+++ b/components/filesystem/directory_impl_unittest.cc
@@ -276,6 +276,18 @@ TEST_F(DirectoryImplTest, CantWriteFileOnADirectory) {
   }
 }
 
+TEST_F(DirectoryImplTest, Flush) {
+  mojom::DirectoryPtr directory;
+  GetTemporaryRoot(&directory);
+  mojom::FileError error;
+
+  {
+    bool handled = directory->Flush(&error);
+    ASSERT_TRUE(handled);
+    EXPECT_EQ(mojom::FileError::OK, error);
+  }
+}
+
 // TODO(vtl): Test delete flags.
 
 }  // namespace