Update GC stats, ThreadPool, Timer and ScopedTimer to use monotonic time.

runtime/vm/thread_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
 #include "vm/unit_test.h"
 #include "vm/profiler.h"
 #include "vm/safepoint.h"
@@ skipping 34 matching lines @@
   Monitor* monitor = new Monitor();
   monitor->Enter();
   monitor->Exit();
   EXPECT_EQ(true, monitor->TryEnter());
   monitor->Exit();
 
   const int kNumAttempts = 5;
   int attempts = 0;
   while (attempts < kNumAttempts) {
     MonitorLocker ml(monitor);
-    int64_t start = OS::GetCurrentTimeMillis();
+    int64_t start = OS::GetCurrentMonotonicMicros();
     int64_t wait_time = 2017;
     Monitor::WaitResult wait_result = ml.Wait(wait_time);
-    int64_t stop = OS::GetCurrentTimeMillis();
+    int64_t stop = OS::GetCurrentMonotonicMicros();
 
     // We expect to be timing out here.
     EXPECT_EQ(Monitor::kTimedOut, wait_result);
 
     // Check whether this attempt falls within the exptected time limits.
-    int64_t wakeup_time = stop - start;
+    int64_t wakeup_time = (stop - start) / kMicrosecondsPerMillisecond;
     OS::Print("wakeup_time: %" Pd64 "\n", wakeup_time);
     const int kAcceptableTimeJitter = 20;    // Measured in milliseconds.
     const int kAcceptableWakeupDelay = 150;  // Measured in milliseconds.
     if (((wait_time - kAcceptableTimeJitter) <= wakeup_time) &&
         (wakeup_time <= (wait_time + kAcceptableWakeupDelay))) {
       break;
     }
 
     // Record the attempt.
     attempts++;
@@ skipping 717 matching lines @@
       TransitionVMToBlocked transition(thread);
       MonitorLocker ml(&done_monitor);
       if (done) {
         break;
       }
     }
   }
 }
 
 }  // namespace dart