Support AudioContextOptions latencyHint as double.

media/base/audio_latency.h

Index: media/base/audio_latency.h
diff --git a/media/base/audio_latency.h b/media/base/audio_latency.h
index c6c44f9cebd70176766d097adf47db42af19feb2..823c3c5da6ac3d37d787e7dcb7ee7cb4584c68e5 100644
--- a/media/base/audio_latency.h
+++ b/media/base/audio_latency.h
@@ -7,8 +7,14 @@
 
 #include "media/base/media_export.h"
 
+namespace base {
+class TimeDelta;
+}
+
 namespace media {
 
+class AudioParameters;
+
 class MEDIA_EXPORT AudioLatency {
  public:
   // Categories of expected latencies for input/output audio. Do not change
@@ -35,6 +41,9 @@ class MEDIA_EXPORT AudioLatency {
   static int GetRtcBufferSize(int sample_rate, int hardware_buffer_size);
 
   static int GetInteractiveBufferSize(int hardware_buffer_size);
+
+  static int GetExactBufferSize(base::TimeDelta duration,
+                                const AudioParameters& hardware_params);
 };
 
 }  // namespace media