Implement a new child test helper for Android.

ipc/mojo/run_all_unittests.cc

 // Copyright 2014 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 "base/at_exit.h"
 #include "base/bind.h"
 #include "base/test/launcher/unit_test_launcher.h"
+#include "base/test/multiprocess_test.h"
 #include "base/test/test_io_thread.h"
 #include "base/test/test_suite.h"
 #include "build/build_config.h"
 #include "mojo/edk/embedder/embedder.h"
 #include "mojo/edk/test/scoped_ipc_support.h"
 
 #if defined(OS_ANDROID)
 #include "base/android/jni_android.h"
 #include "base/test/test_file_util.h"
 #endif
 
 int main(int argc, char** argv) {
 #if defined(OS_ANDROID)
+  // Enable the alternate test child implementation. This is needed because Mojo
+  // tests need to spawn test children after initialising the Mojo system.
+  base::InitAndroidMultiProcessTestHelper(main);
+
   JNIEnv* env = base::android::AttachCurrentThread();
   base::RegisterContentUriTestUtils(env);
 #endif
   base::TestSuite test_suite(argc, argv);
   mojo::edk::Init();
   base::TestIOThread test_io_thread(base::TestIOThread::kAutoStart);
   // Leak this because its destructor calls mojo::edk::ShutdownIPCSupport which
   // really does nothing in the new EDK but does depend on the current message
   // loop, which is destructed inside base::LaunchUnitTests.
   new mojo::edk::test::ScopedIPCSupport(test_io_thread.task_runner());
   return base::LaunchUnitTestsSerially(
       argc, argv,
       base::Bind(&base::TestSuite::Run, base::Unretained(&test_suite)));
 }