Adding the ability to use a simulated clock for unit tests.

webrtc/base/timeutils.cc

Index: webrtc/base/timeutils.cc
diff --git a/webrtc/base/timeutils.cc b/webrtc/base/timeutils.cc
index de3e6afb28d824ecb9dfc26f1029dd0d0958fd24..a43158712d7776a0cb88bece684a8d6c369b6422 100644
--- a/webrtc/base/timeutils.cc
+++ b/webrtc/base/timeutils.cc
@@ -32,7 +32,16 @@ namespace rtc {
 
 const uint32_t HALF = 0x80000000;
 
+ClockInterface* clock_ = nullptr;
+
+void SetClock(ClockInterface* clock) {
+  clock_ = clock;
+}
+
 uint64_t TimeNanos() {
+  if (clock_) {

[juberti2, 2016/04/25 20:18:23]

Do we need to mention that this is unsynchronized?

[Taylor Brandstetter, 2016/04/26 01:22:32]

I mention in timeutils.h that SetClock (which is the only thing that modifies
clock_) isn't thread-safe.

+    return clock_->TimeNanos();
+  }
   int64_t ticks = 0;
 #if defined(WEBRTC_MAC)

[juberti2, 2016/04/25 20:18:23]

Should we factor this into a real clock implementation?

[Taylor Brandstetter, 2016/04/26 01:22:32]

Done.

   static mach_timebase_info_data_t timebase;