Clean up audio-related utility functions to compute buffer sizes

content/renderer/media/audio_hardware.cc

Index: content/renderer/media/audio_hardware.cc
diff --git a/content/renderer/media/audio_hardware.cc b/content/renderer/media/audio_hardware.cc
index 183ebecd529510bea3e2d132f02ebe447f44ea10..1f49fdb991103682a94fe09a49f9693b51dff643 100644
--- a/content/renderer/media/audio_hardware.cc
+++ b/content/renderer/media/audio_hardware.cc
@@ -48,6 +48,31 @@ size_t GetOutputBufferSize() {
   return output_buffer_size;
 }
 
+size_t GetHighLatencyOutputBufferSize(int sample_rate) {
+  // The minimum number of samples in a hardware packet.
+  // This value is selected so that we can handle down to 5khz sample rate.
+  static const size_t kMinSamplesPerHardwarePacket = 1024;
+
+  // The maximum number of samples in a hardware packet.
+  // This value is selected so that we can handle up to 192khz sample rate.
+  static const size_t kMaxSamplesPerHardwarePacket = 64 * 1024;
+
+  // This constant governs the hardware audio buffer size, this value should be
+  // chosen carefully.
+  // This value is selected so that we have 8192 samples for 48khz streams.
+  static const size_t kMillisecondsPerHardwarePacket = 170;
+
+  // Select the number of samples that can provide at least
+  // |kMillisecondsPerHardwarePacket| worth of audio data.
+  size_t samples = kMinSamplesPerHardwarePacket;
+  while (samples <= kMaxSamplesPerHardwarePacket &&
+         samples * base::Time::kMillisecondsPerSecond <
+         sample_rate * kMillisecondsPerHardwarePacket) {
+    samples *= 2;
+  }
+  return samples;
+}
+
 uint32 GetInputChannelCount() {
   DCHECK(RenderThreadImpl::current() != NULL);