Convert media constants to constexpr.

media/base/time_delta_interpolator.cc

Index: media/base/time_delta_interpolator.cc
diff --git a/media/base/time_delta_interpolator.cc b/media/base/time_delta_interpolator.cc
index aea174c1114d96d35bcb29543a2ff66b8b0b2adb..9000093fc0c7d45b172712519071f48c817b93c3 100644
--- a/media/base/time_delta_interpolator.cc
+++ b/media/base/time_delta_interpolator.cc
@@ -17,7 +17,7 @@ namespace media {
 TimeDeltaInterpolator::TimeDeltaInterpolator(base::TickClock* tick_clock)
     : tick_clock_(tick_clock),
       interpolating_(false),
-      upper_bound_(kNoTimestamp()),
+      upper_bound_(kNoTimestamp),
       playback_rate_(1.0) {
   DCHECK(tick_clock_);
 }
@@ -48,7 +48,7 @@ void TimeDeltaInterpolator::SetPlaybackRate(double playback_rate) {
 void TimeDeltaInterpolator::SetBounds(base::TimeDelta lower_bound,
                                       base::TimeDelta upper_bound) {
   DCHECK(lower_bound <= upper_bound);
-  DCHECK(lower_bound != kNoTimestamp());
+  DCHECK(lower_bound != kNoTimestamp);
 
   lower_bound_ = std::max(base::TimeDelta(), lower_bound);
   upper_bound_ = std::max(base::TimeDelta(), upper_bound);
@@ -56,7 +56,7 @@ void TimeDeltaInterpolator::SetBounds(base::TimeDelta lower_bound,
 }
 
 void TimeDeltaInterpolator::SetUpperBound(base::TimeDelta upper_bound) {
-  DCHECK(upper_bound != kNoTimestamp());
+  DCHECK(upper_bound != kNoTimestamp);
 
   lower_bound_ = GetInterpolatedTime();
   reference_ = tick_clock_->NowTicks();
@@ -72,7 +72,7 @@ base::TimeDelta TimeDeltaInterpolator::GetInterpolatedTime() {
   base::TimeDelta interpolated_time =
       lower_bound_ + base::TimeDelta::FromMicroseconds(now_us);
 
-  if (upper_bound_ == kNoTimestamp())
+  if (upper_bound_ == kNoTimestamp)
     return interpolated_time;
 
   return std::min(interpolated_time, upper_bound_);