Mojo: (POSIX) Pass channel handle to child.

mojo/common/test/multiprocess_test_base_unittest.cc

 // Copyright 2013 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 "mojo/common/test/multiprocess_test_base.h"
 
+#include "base/logging.h"
+// TODO(vtl): Remove build_config.h include when fully implemented on Windows.
+#include "build/build_config.h"
+
 namespace mojo {
 namespace {
 
 class MultiprocessTestBaseTest : public test::MultiprocessTestBase {
 };
 
 TEST_F(MultiprocessTestBaseTest, RunChild) {
   StartChild("RunChild");
   EXPECT_EQ(123, WaitForChildShutdown());
 }
 
 MOJO_MULTIPROCESS_TEST_CHILD_MAIN(RunChild) {
+// TODO(vtl): Not implemented on Windows yet.
+#if defined(OS_POSIX)
+  CHECK(MultiprocessTestBaseTest::platform_client_channel.get());
+  CHECK(MultiprocessTestBaseTest::platform_client_channel->is_valid());
+  // TODO(vtl): Check the client channel.
+#endif
   return 123;
 }
 
 TEST_F(MultiprocessTestBaseTest, TestChildMainNotFound) {
   StartChild("NoSuchTestChildMain");
   int result = WaitForChildShutdown();
   EXPECT_FALSE(result >= 0 && result <= 127);
 }
 
 }  // namespace
 }  // namespace mojo