Express audio delay more precisely in frames rather than milliseconds.

media/audio/audio_output_device.cc

Index: media/audio/audio_output_device.cc
diff --git a/media/audio/audio_output_device.cc b/media/audio/audio_output_device.cc
index 3af32b7835f8f1f8a23c98b0a0a16f7fa4deb31c..7044e9ae770649c0477b9b37af56eca6fff01abb 100644
--- a/media/audio/audio_output_device.cc
+++ b/media/audio/audio_output_device.cc
@@ -6,6 +6,8 @@
 
 #include <stddef.h>
 #include <stdint.h>
+
+#include <cmath>
 #include <utility>
 
 #include "base/callback_helpers.h"
@@ -413,8 +415,8 @@ void AudioOutputDevice::AudioThreadCallback::MapSharedMemory() {
 
 // Called whenever we receive notifications about pending data.
 void AudioOutputDevice::AudioThreadCallback::Process(uint32_t pending_data) {
-  // Convert the number of pending bytes in the render buffer into milliseconds.
-  uint32_t audio_delay_milliseconds = pending_data / bytes_per_ms_;
+  // Convert the number of pending bytes in the render buffer into frames.
+  double frames_delayed = static_cast<double>(pending_data) / bytes_per_frame_;
 
   callback_num_++;
   TRACE_EVENT1("audio", "AudioOutputDevice::FireRenderCallback",
@@ -433,11 +435,15 @@ void AudioOutputDevice::AudioThreadCallback::Process(uint32_t pending_data) {
   uint32_t frames_skipped = buffer->params.frames_skipped;
   buffer->params.frames_skipped = 0;
 
+  DVLOG(4) << __FUNCTION__ << " pending_data:" << pending_data
+           << " frames_delayed(pre-round):" << frames_delayed
+           << " frames_skipped:" << frames_skipped;
+
   // Update the audio-delay measurement, inform about the number of skipped
   // frames, and ask client to render audio.  Since |output_bus_| is wrapping
   // the shared memory the Render() call is writing directly into the shared
   // memory.
-  render_callback_->Render(output_bus_.get(), audio_delay_milliseconds,
+  render_callback_->Render(output_bus_.get(), std::round(frames_delayed),
                            frames_skipped);
 }