Change NetEq::GetPlayoutTimestamp to return an rtc::Optional<uint32_t>

webrtc/modules/audio_coding/acm2/audio_coding_module_impl.cc

Index: webrtc/modules/audio_coding/acm2/audio_coding_module_impl.cc
diff --git a/webrtc/modules/audio_coding/acm2/audio_coding_module_impl.cc b/webrtc/modules/audio_coding/acm2/audio_coding_module_impl.cc
index d30daaaf3407f6a221d987eca57ba3917429fee8..254c2f420bf097c333527f82285094594bfc7c45 100644
--- a/webrtc/modules/audio_coding/acm2/audio_coding_module_impl.cc
+++ b/webrtc/modules/audio_coding/acm2/audio_coding_module_impl.cc
@@ -902,8 +902,16 @@ int AudioCodingModuleImpl::DisableOpusDtx() {
   return encoder_stack_->SetDtx(false) ? 0 : -1;
 }
 
-int AudioCodingModuleImpl::PlayoutTimestamp(uint32_t* timestamp) {
-  return receiver_.GetPlayoutTimestamp(timestamp) ? 0 : -1;
+int32_t AudioCodingModuleImpl::PlayoutTimestamp(uint32_t* timestamp) {
+  rtc::Optional<uint32_t> ts = PlayoutTimestamp();
+  if (!ts)
+    return -1;
+  *timestamp = *ts;
+  return 0;
+}
+
+rtc::Optional<uint32_t> AudioCodingModuleImpl::PlayoutTimestamp() {
+  return receiver_.GetPlayoutTimestamp();
 }
 
 bool AudioCodingModuleImpl::HaveValidEncoder(const char* caller_name) const {