EDK: Move mutex.*, cond_var.*, and thread_annotations.h to //mojo/edk/util.

mojo/edk/system/message_pipe.h

Index: mojo/edk/system/message_pipe.h
diff --git a/mojo/edk/system/message_pipe.h b/mojo/edk/system/message_pipe.h
index 2d161e10dfa63ce1e29ed634764ff081e1530480..99b120086177ebc597b805549fa8f32d2b27dec3 100644
--- a/mojo/edk/system/message_pipe.h
+++ b/mojo/edk/system/message_pipe.h
@@ -18,8 +18,9 @@
 #include "mojo/edk/system/memory.h"
 #include "mojo/edk/system/message_in_transit.h"
 #include "mojo/edk/system/message_pipe_endpoint.h"
-#include "mojo/edk/system/mutex.h"
+#include "mojo/edk/util/mutex.h"
 #include "mojo/edk/util/ref_ptr.h"
+#include "mojo/edk/util/thread_annotations.h"
 #include "mojo/public/c/system/message_pipe.h"
 #include "mojo/public/c/system/types.h"
 #include "mojo/public/cpp/system/macros.h"
@@ -137,7 +138,7 @@ class MessagePipe final : public ChannelEndpointClient {
       std::vector<DispatcherTransport>* transports)
       MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
-  mutable Mutex mutex_;
+  mutable util::Mutex mutex_;
   std::unique_ptr<MessagePipeEndpoint> endpoints_[2] MOJO_GUARDED_BY(mutex_);
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessagePipe);