Convert media constants to constexpr.

media/formats/mp2t/es_adapter_video.cc

Index: media/formats/mp2t/es_adapter_video.cc
diff --git a/media/formats/mp2t/es_adapter_video.cc b/media/formats/mp2t/es_adapter_video.cc
index bc048272e3a208ab95c024feb7226ecc50110100..e33339672a178669570898707e3237461b696f80 100644
--- a/media/formats/mp2t/es_adapter_video.cc
+++ b/media/formats/mp2t/es_adapter_video.cc
@@ -75,7 +75,7 @@ void EsAdapterVideo::OnConfigChanged(
 
 bool EsAdapterVideo::OnNewBuffer(
     const scoped_refptr<StreamParserBuffer>& stream_parser_buffer) {
-  if (stream_parser_buffer->timestamp() == kNoTimestamp()) {
+  if (stream_parser_buffer->timestamp() == kNoTimestamp) {
     if (has_valid_frame_) {
       // There is currently no error concealment for a missing timestamp
       // in the middle of the stream.
@@ -143,9 +143,9 @@ void EsAdapterVideo::ProcessPendingBuffers(bool flush) {
     buffer_list_.pop_front();
     buffer_index_++;
 
-    if (buffer->duration() == kNoTimestamp()) {
+    if (buffer->duration() == kNoTimestamp) {
       base::TimeDelta next_frame_pts = GetNextFramePts(buffer->timestamp());
-      if (next_frame_pts == kNoTimestamp()) {
+      if (next_frame_pts == kNoTimestamp) {
         // This can happen when emitting the very last buffer
         // or if the stream do not meet the assumption behind |kHistorySize|.
         DVLOG(LOG_LEVEL_ES) << "Using last frame duration: "
@@ -168,7 +168,7 @@ void EsAdapterVideo::ProcessPendingBuffers(bool flush) {
 }
 
 base::TimeDelta EsAdapterVideo::GetNextFramePts(base::TimeDelta current_pts) {
-  base::TimeDelta next_pts = kNoTimestamp();
+  base::TimeDelta next_pts = kNoTimestamp;
 
   // Consider the timestamps of future frames (in decode order).
   // Note: the next frame is not enough when the GOP includes some B frames.
@@ -176,7 +176,7 @@ base::TimeDelta EsAdapterVideo::GetNextFramePts(base::TimeDelta current_pts) {
        it != buffer_list_.end(); ++it) {
     if ((*it)->timestamp() < current_pts)
       continue;
-    if (next_pts == kNoTimestamp() || next_pts > (*it)->timestamp())
+    if (next_pts == kNoTimestamp || next_pts > (*it)->timestamp())
       next_pts = (*it)->timestamp();
   }
 
@@ -187,7 +187,7 @@ base::TimeDelta EsAdapterVideo::GetNextFramePts(base::TimeDelta current_pts) {
        it != emitted_pts_.end(); ++it) {
     if (*it < current_pts)
       continue;
-    if (next_pts == kNoTimestamp() || next_pts > *it)
+    if (next_pts == kNoTimestamp || next_pts > *it)
       next_pts = *it;
   }