Delete all use of tick_util.h.

webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc

Index: webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
diff --git a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
index 4a22e3d31fd506fadb7838048a752bf42607f5bc..589eb5999f0401c66203154a8ec5e0ae79e8ce07 100644
--- a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
+++ b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
@@ -22,13 +22,13 @@
 #include "vpx/vp8dx.h"
 
 #include "webrtc/base/checks.h"
+#include "webrtc/base/timeutils.h"
 #include "webrtc/base/keep_ref_until_done.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/trace_event.h"
 #include "webrtc/common_video/libyuv/include/webrtc_libyuv.h"
 #include "webrtc/modules/include/module_common_types.h"
 #include "webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h"
-#include "webrtc/system_wrappers/include/tick_util.h"
 
 namespace webrtc {
 
@@ -77,7 +77,7 @@ VP9EncoderImpl::VP9EncoderImpl()
       // Use two spatial when screensharing with flexible mode.
       spatial_layer_(new ScreenshareLayersVP9(2)) {
   memset(&codec_, 0, sizeof(codec_));
-  uint32_t seed = static_cast<uint32_t>(TickTime::MillisecondTimestamp());
+  uint32_t seed = rtc::Time32();
   srand(seed);
 }