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

BUG=webrtc:6324

Review-Url: https://codereview.webrtc.org/2290203002
Cr-Commit-Position: refs/heads/master@{#14203}
diff --git a/webrtc/base/timeutils.cc b/webrtc/base/timeutils.cc
index 1be368e..658d079 100644
--- a/webrtc/base/timeutils.cc
+++ b/webrtc/base/timeutils.cc
@@ -23,6 +23,7 @@
 #endif
 #include <windows.h>
 #include <mmsystem.h>
+#include <sys/timeb.h>
 #endif
 
 #include "webrtc/base/checks.h"
@@ -185,4 +186,21 @@
             (year - 1970) * 365 + day) * 24 + hour) * 60 + min) * 60 + sec;
 }
 
+int64_t TimeUTCMicros() {
+#if defined(WEBRTC_POSIX)
+  struct timeval time;
+  gettimeofday(&time, NULL);
+  // Convert from second (1.0) and microsecond (1e-6).
+  return (static_cast<int64_t>(time.tv_sec) * rtc::kNumMicrosecsPerSec +
+          time.tv_usec);
+
+#elif defined(WEBRTC_WIN)
+  struct _timeb time;
+  _ftime(&time);
+  // Convert from second (1.0) and milliseconds (1e-3).
+  return (static_cast<int64_t>(time.time) * rtc::kNumMicrosecsPerSec +
+          static_cast<int64_t>(time.millitm) * rtc::kNumMicrosecsPerMillisec);
+#endif
+}
+
 } // namespace rtc