Support AudioContextOptions latencyHint as double.

media/base/audio_latency.cc

Index: media/base/audio_latency.cc
diff --git a/media/base/audio_latency.cc b/media/base/audio_latency.cc
index 5d37edf415213ff72aeb6e9753927abf1dfb8894..96f6f7d92827cf25b0f2b3841188214e731532c8 100644
--- a/media/base/audio_latency.cc
+++ b/media/base/audio_latency.cc
@@ -10,6 +10,7 @@
 
 #include "base/logging.h"
 #include "build/build_config.h"
+#include "media/base/audio_parameters.h"
 
 namespace media {
 
@@ -126,4 +127,12 @@ int AudioLatency::GetInteractiveBufferSize(int hardware_buffer_size) {
   return hardware_buffer_size;
 }
 
+int AudioLatency::GetExactBufferSize(double duration,
+                                     const AudioParameters& hardware_params) {
+  return std::max(
+      std::min(static_cast<int>(duration * hardware_params.sample_rate()),
+               GetHighLatencyBufferSize(hardware_params.sample_rate(), 0)),
+      static_cast<int>(hardware_params.frames_per_buffer()));
+}
+
 }  // namespace media