Several Tick counter improvements.

webrtc/modules/utility/source/process_thread_impl_unittest.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 233 matching lines @@
 // Tests that we can wake up the worker thread to give us a callback right
 // away when we know the thread is sleeping.
 TEST(ProcessThreadImpl, WakeUp) {
   ProcessThreadImpl thread("ProcessThread");
   thread.Start();
 
   rtc::scoped_ptr<EventWrapper> started(EventWrapper::Create());
   rtc::scoped_ptr<EventWrapper> called(EventWrapper::Create());
 
   MockModule module;
   int64_t start_time = 0;

[pbos-webrtc, 2015/11/12 11:55:41]

Shouldn't you initialize these to -1 and update the asserts below instead (that
it's > -1)?

[noahric, 2015/11/12 18:10:15]

I think we should actually just the startTime != something check;
MillisecondTimestamp and family make no claims about the absolute values of the
value they return, so this could legally return anything for the first value,
including -1. That's what I exploited when writing this originally (deltas from
zero mean small values, so loss of precision is acceptable over certain
timeframes).

   int64_t called_time = 0;
+
+  // On Mac, timestamps start at 0 the first time TickTime::Foo is called.
+  // Let this increment a very small amount before comparing our elapsed times.
+  (void)TickTime::MillisecondTimestamp();
+  started->Wait(10);
+
   // Ask for a callback after 1000ms.
   // TimeUntilNextProcess will be called twice.
   // The first time we use it to get the thread into a waiting state.
   // Then we  wake the thread and there should not be another call made to
   // TimeUntilNextProcess before Process() is called.
   // The second time TimeUntilNextProcess is then called, is after Process
   // has been called and we don't expect any more calls.
   EXPECT_CALL(module, TimeUntilNextProcess())
       .WillOnce(DoAll(SetTimestamp(&start_time),
                       SetEvent(started.get()),
@@ skipping 29 matching lines @@
   ProcessThreadImpl thread("ProcessThread");
   rtc::scoped_ptr<EventWrapper> task_ran(EventWrapper::Create());
   rtc::scoped_ptr<RaiseEventTask> task(new RaiseEventTask(task_ran.get()));
   thread.Start();
   thread.PostTask(task.Pass());
   EXPECT_EQ(kEventSignaled, task_ran->Wait(100));
   thread.Stop();
 }
 
 }  // namespace webrtc