Adding Media.InputStreamDuration to UMA histograms for low-latency input audio streams

media/audio/audio_input_controller.h

Index: media/audio/audio_input_controller.h
diff --git a/media/audio/audio_input_controller.h b/media/audio/audio_input_controller.h
index 691f1afb05bb75734e731274a7347622a9d40360..8a1d3fb3b0d1ddabef385bd2fa0ab6de5ec52c7b 100644
--- a/media/audio/audio_input_controller.h
+++ b/media/audio/audio_input_controller.h
@@ -369,6 +369,9 @@ class MEDIA_EXPORT AudioInputController
 
   size_t prev_key_down_count_;
 
+  // Time when a low-latency stream is created.
+  base::TimeTicks low_latency_create_time_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioInputController);
 };