Use ThreadNow() for recording times.

If available, this CL changes RenderingStatsInstrumentation to use
ThreadNow() instead of HighResNow(). ThreadNow should provide a more accurate
benchmark as it will exclude time when the thread is descheduled.

BUG=280638

Review URL: https://chromiumcodereview.appspot.com/23523026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221591 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 8 insertions, 2 deletions

diff --git a/cc/debug/rendering_stats_instrumentation.cc b/cc/debug/rendering_stats_instrumentation.cc
index 2c5b252..3c2c96b 100644
--- a/cc/debug/rendering_stats_instrumentation.cc
+++ b/cc/debug/rendering_stats_instrumentation.cc
@@ -39,15 +39,21 @@ void RenderingStatsInstrumentation::AccumulateAndClearImplThreadStats() {
 }
 
 base::TimeTicks RenderingStatsInstrumentation::StartRecording() const {
-  if (record_rendering_stats_)
+  if (record_rendering_stats_) {
+    if (base::TimeTicks::IsThreadNowSupported())
+      return base::TimeTicks::ThreadNow();
     return base::TimeTicks::HighResNow();
+  }
   return base::TimeTicks();
 }
 
 base::TimeDelta RenderingStatsInstrumentation::EndRecording(
     base::TimeTicks start_time) const {
-  if (!start_time.is_null())
+  if (!start_time.is_null()) {
+    if (base::TimeTicks::IsThreadNowSupported())
+      return base::TimeTicks::ThreadNow() - start_time;
     return base::TimeTicks::HighResNow() - start_time;
+  }
   return base::TimeDelta();
 }