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

mojo/edk/system/slave_connection_manager.h

Index: mojo/edk/system/slave_connection_manager.h
diff --git a/mojo/edk/system/slave_connection_manager.h b/mojo/edk/system/slave_connection_manager.h
index bd66534c91e9464c0a2abfdcd89910356af3b110..c8904bc4f9dd8a38c89efdbb4de41286f70ab9a3 100644
--- a/mojo/edk/system/slave_connection_manager.h
+++ b/mojo/edk/system/slave_connection_manager.h
@@ -14,8 +14,8 @@
 #include "mojo/edk/embedder/slave_process_delegate.h"
 #include "mojo/edk/system/connection_manager.h"
 #include "mojo/edk/system/raw_channel.h"
-#include "mojo/edk/system/waitable_event.h"
 #include "mojo/edk/util/mutex.h"
+#include "mojo/edk/util/waitable_event.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace base {
@@ -147,7 +147,7 @@ class SlaveConnectionManager final : public ConnectionManager,
   // TODO(vtl): This is all a hack. It'd really suffice to have a version of
   // |RawChannel| with fully synchronous reading and writing.
   util::Mutex mutex_;
-  AutoResetWaitableEvent event_;
+  util::AutoResetWaitableEvent event_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(SlaveConnectionManager);
 };