Delete Timing class, timing.h, and update all users.

webrtc/base/timeutils.h

Index: webrtc/base/timeutils.h
diff --git a/webrtc/base/timeutils.h b/webrtc/base/timeutils.h
index 25ef52105cdfa91afd038ee66dd98f2e3bd7f4f7..f550f1f30201f43d2e85f735f05558fc847a8be1 100644
--- a/webrtc/base/timeutils.h
+++ b/webrtc/base/timeutils.h
@@ -108,6 +108,9 @@ class TimestampWrapAroundHandler {
 // is still 32 bits on many systems.
 int64_t TmToSeconds(const std::tm& tm);
 
+// Returns number of microseconds since January 1, 1970, UTC.

[hbos, 2016/09/08 07:50:43]

Comment about it being the wall clock and that it could change, e.g. not
monotonically increasing, don't use for measuring time between two calls.

[nisse-webrtc, 2016/09/08 09:07:14]

I've added a comment on proper and improper use.

+int64_t TimeUTCMicros();
+
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_TIMEUTILS_H_