Reland: Implement NetEq's CurrentDelay function

webrtc/modules/audio_coding/neteq/neteq_impl.cc

Index: webrtc/modules/audio_coding/neteq/neteq_impl.cc
diff --git a/webrtc/modules/audio_coding/neteq/neteq_impl.cc b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
index 22e71f7f1d8af82f80d3f46c38cf465c84da7f4e..77e245db9d0598d3f7b357c8bd8fb0e809c9f084 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
@@ -15,6 +15,7 @@
 
 #include <algorithm>
 
+#include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/safe_conversions.h"
 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
@@ -282,8 +283,20 @@ int NetEqImpl::TargetDelay() {
   return kNotImplemented;
 }
 
-int NetEqImpl::CurrentDelay() {
-  return kNotImplemented;
+int NetEqImpl::CurrentDelayMs() const {
+  CriticalSectionScoped lock(crit_sect_.get());
+  if (fs_hz_ == 0)
+    return 0;
+  // Sum up the samples in the packet buffer with the future length of the sync
+  // buffer, and divide the sum by the sample rate.
+  const size_t delay_samples =
+      packet_buffer_->NumSamplesInBuffer(decoder_database_.get(),
+                                         decoder_frame_length_) +
+      sync_buffer_->FutureLength();
+  // The division below will truncate.
+  const int delay_ms =
+      static_cast<int>(delay_samples) / rtc::CheckedDivExact(fs_hz_, 1000);
+  return delay_ms;
 }
 
 // Deprecated.