Add //mojo/edk/platform/thread_utils.* containing "yield" and "sleep".

mojo/edk/util/cond_var_unittest.cc

 // 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.
 
 #include "mojo/edk/util/cond_var.h"
 
 #include <stdint.h>
 #include <stdlib.h>
 
 #include <thread>
 #include <type_traits>
 #include <vector>
 
-#include "mojo/edk/system/test/sleep.h"
+#include "mojo/edk/platform/thread_utils.h"
 #include "mojo/edk/system/test/stopwatch.h"
 #include "mojo/edk/system/test/timeouts.h"
 #include "mojo/edk/util/mutex.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+using mojo::platform::ThreadSleep;
 using mojo::system::test::DeadlineFromMilliseconds;
 using mojo::system::test::EpsilonTimeout;
-using mojo::system::test::SleepMilliseconds;
 using mojo::system::test::Stopwatch;
 using mojo::system::test::TinyTimeout;
 
 namespace mojo {
 namespace util {
 namespace {
 
 // Sleeps for a "very small" amount of time.
 void EpsilonRandomSleep() {
-  SleepMilliseconds(static_cast<unsigned>(rand()) % 20u);
+  ThreadSleep(DeadlineFromMilliseconds(static_cast<unsigned>(rand()) % 20u));
 }
 
 // We'll use |MojoDeadline| with |uint64_t| (for |CondVar::WaitWithTimeout()|'s
 // timeout argument), though note that |WaitWithTimeout()| doesn't support
 // |MOJO_DEADLINE_INDEFINITE|.
 static_assert(std::is_same<uint64_t, MojoDeadline>::value,
               "MojoDeadline isn't uint64_t!");
 
 TEST(CondVarTest, Basic) {
   // Create/destroy.
@@ skipping 123 matching lines @@
     // But we expect that it should time out soon after that amount of time.
     EXPECT_LT(elapsed, timeout + EpsilonTimeout());
   }
 }
 
 // TODO(vtl): Test that |Signal()| (usually) wakes only one waiter.
 
 }  // namespace
 }  // namespace util
 }  // namespace mojo