Mojo: Always use Now() instead of HighResNow().

This will hopefully fix/reduce flakiness of
MessagePipeDispatcherTest.BasicThreaded on Windows. This is a no-op on
Mac and non-Mac POSIX (where Now() and HighResNow() are the same).

Apparently, the canonical time is "Now". Our current, weird
implementation of PlatformThread::Sleep() for Windows is:

  // When measured with a high resolution clock, Sleep() sometimes returns much
  // too early. We may need to call it repeatedly to get the desired duration.
  TimeTicks end = TimeTicks::Now() + duration;
  TimeTicks now;
  while ((now = TimeTicks::Now()) < end)
    ::Sleep((end - now).InMillisecondsRoundedUp());

Of course, if Now() is *not* the high res timer ... who knows what the
effect of this is versus HighResNow(). (We could end up having slept for
much longer -- as measured by HighResNow() -- than we wanted. This seems
to be the symptom of this particular flakiness.)

On the other hand, who knows what timer the timeouts of
WaitForSingleObject(), etc. are relative to. So the correctness of times
in Chromium on Windows is highly suspect.

R=yzshen@chromium.org
BUG=387513

Review URL: https://codereview.chromium.org/354533003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@279413 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 2 insertions, 2 deletions

diff --git a/mojo/system/waiter.cc b/mojo/system/waiter.cc
index 5a3150d..381f9bb 100644
--- a/mojo/system/waiter.cc
+++ b/mojo/system/waiter.cc
@@ -64,10 +64,10 @@ MojoResult Waiter::Wait(MojoDeadline deadline, uint32_t* context) {
   } else {
     // NOTE(vtl): This is very inefficient on POSIX, since pthreads condition
     // variables take an absolute deadline.
-    const base::TimeTicks end_time = base::TimeTicks::HighResNow() +
+    const base::TimeTicks end_time = base::TimeTicks::Now() +
         base::TimeDelta::FromMicroseconds(static_cast<int64_t>(deadline));
     do {
-      base::TimeTicks now_time = base::TimeTicks::HighResNow();
+      base::TimeTicks now_time = base::TimeTicks::Now();
       if (now_time >= end_time)
         return MOJO_RESULT_DEADLINE_EXCEEDED;