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

mojo/edk/system/cond_var.h

-// Copyright 2015 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.
-
-// A condition variable class (to be used with |mojo::system::Mutex|).
-
-#ifndef MOJO_EDK_SYSTEM_COND_VAR_H_
-#define MOJO_EDK_SYSTEM_COND_VAR_H_
-
-#include <pthread.h>
-#include <stdint.h>
-
-#include "mojo/edk/system/thread_annotations.h"
-#include "mojo/public/cpp/system/macros.h"
-
-namespace mojo {
-namespace system {
-
-class Mutex;
-
-class CondVar {
- public:
-  CondVar();
-  ~CondVar();
-
-  // Atomically releases |*mutex| (which must be held) and blocks on this
-  // condition variable, unlocking and reacquiring |*mutex| when:
-  //   * |SignalAll()| is called,
-  //   * |Signal()| is called and this thread is scheduled to be the next to be
-  //     unblocked, or
-  //   * whenever (spuriously, e.g., due to |EINTR|).
-  // To deal with spurious wakeups, wait using a loop (with |my_mutex| held):
-  //   while (!<my_condition>)
-  //     cv.Wait(&my_mutex);
-  void Wait(Mutex* mutex) MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex);
-
-  // Like |Wait()|, but will also unblock when |timeout_microseconds| have
-  // elapsed without this condition variable being signaled. Returns true on
-  // timeout; this is somewhat counterintuitive, but the false case is
-  // non-specific: the condition variable may or may not have been signaled and
-  // |timeout_microseconds| may or may not have already elapsed (spurious
-  // wakeups are possible).
-  // TODO(vtl): A version with an absolute deadline time would be more efficient
-  // for users who want to wait to be signaled or a timeout to have definitely
-  // elapsed. With this API, users have to recalculate the timeout when they
-  // detect a spurious wakeup.
-  bool WaitWithTimeout(Mutex* mutex, uint64_t timeout_microseconds)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex);
-
-  // Signals this condition variable, waking at least one waiting thread if
-  // there are any.
-  void Signal();
-
-  // Signals this condition variable, waking all waiting threads.
-  void SignalAll();
-
- private:
-  pthread_cond_t impl_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(CondVar);
-};
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // MOJO_EDK_SYSTEM_COND_VAR_H_