Revert "EDK: Move //mojo/edk/system/waitable_event* to edk/util."

mojo/edk/system/dispatcher_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/edk/system/dispatcher.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/logging.h"
 #include "mojo/edk/embedder/platform_shared_buffer.h"
 #include "mojo/edk/system/memory.h"
 #include "mojo/edk/system/test/simple_test_thread.h"
+#include "mojo/edk/system/waitable_event.h"
 #include "mojo/edk/system/waiter.h"
 #include "mojo/edk/util/make_unique.h"
 #include "mojo/edk/util/ref_ptr.h"
-#include "mojo/edk/util/waitable_event.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using mojo::util::MakeRefCounted;
-using mojo::util::ManualResetWaitableEvent;
 using mojo::util::RefPtr;
 
 namespace mojo {
 namespace system {
 namespace {
 
 // Trivial subclass that makes the constructor public.
 class TrivialDispatcher final : public Dispatcher {
  public:
   // Note: Use |MakeRefCounted<TrivialDispatcher>()|.
@@ skipping 273 matching lines @@
       event.Signal();
     }  // Joins all the threads.
 
     EXPECT_EQ(MOJO_RESULT_OK, d->Close());
   }
 }
 
 }  // namespace
 }  // namespace system
 }  // namespace mojo