Replace (most) occurrences of mojo::Array<T>() with nullptr.

services/files/file_impl_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <vector>
 
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/type_converter.h"
 #include "services/files/files_test_base.h"
 
@@ skipping 664 matching lines @@
   FilePtr file;
   error = Error::INTERNAL;
   directory->OpenFile("my_file", GetProxy(&file),
                       kOpenFlagRead | kOpenFlagWrite | kOpenFlagCreate,
                       Capture(&error));
   ASSERT_TRUE(directory.WaitForIncomingResponse());
   EXPECT_EQ(Error::OK, error);
 
   // Normal files don't support any ioctls.
   Array<uint32_t> out_values;
-  file->Ioctl(0, Array<uint32_t>(), Capture(&error, &out_values));
+  file->Ioctl(0, nullptr, Capture(&error, &out_values));
   ASSERT_TRUE(file.WaitForIncomingResponse());
   EXPECT_EQ(Error::UNAVAILABLE, error);
   EXPECT_TRUE(out_values.is_null());
 }
 
 }  // namespace
 }  // namespace files
 }  // namespace mojo