Convert rtc_event_log from webrtc::Clock to rtc::TimeMicros.

webrtc/base/fakeclock.h

Index: webrtc/base/fakeclock.h
diff --git a/webrtc/base/fakeclock.h b/webrtc/base/fakeclock.h
index 7fa101558fc741311e19a1a1ca93abcc056a93df..eb78cf864de57b6267948c0c4e7dc83fc3ac0d13 100644
--- a/webrtc/base/fakeclock.h
+++ b/webrtc/base/fakeclock.h
@@ -32,9 +32,14 @@ class FakeClock : public ClockInterface {
 
   // Should only be used to set a time in the future.
   void SetTimeNanos(int64_t nanos);
+  void SetTimeMicros(int64_t micros) {
+    SetTimeNanos(kNumNanosecsPerMicrosec * micros);
+  }
 
   void AdvanceTime(TimeDelta delta);
-
+  void AdvanceTimeMicros(int64_t micros) {
+    AdvanceTime(rtc::TimeDelta::FromMicroseconds(micros));
+  }
  private:
   CriticalSection lock_;
   int64_t time_ GUARDED_BY(lock_) = 0;