Refactor GetPreferredAudioParameters from core audio util on Windows

Split GetPreferredAudioParameters functions to improve readability,
move helper functions to unnamed namespace, fix typo.

R=maxmorin@chromium.org, olka@chromium.org

Bug: 774998
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I630e02dc73152eaf662a94ef0e1a4150a8ebcec9
Reviewed-on: https://chromium-review.googlesource.com/743361Reviewed-by: Olga Sharonova <olka@chromium.org>
Reviewed-by: Max Morin <maxmorin@chromium.org>
Commit-Queue: Marina Ciocea <marinaciocea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512794}

media/audio/win/audio_low_latency_output_win.cc

@@ -180,7 +180,7 @@ bool WASAPIAudioOutputStream::Open() {
 
     const int preferred_frames_per_buffer = static_cast<int>(
         format_.Format.nSamplesPerSec *
-            CoreAudioUtil::RefererenceTimeToTimeDelta(device_period)
+            CoreAudioUtil::ReferenceTimeToTimeDelta(device_period)
                 .InSecondsF() +
         0.5);
 

media/audio/win/core_audio_util_win.h

@@ -43,7 +43,7 @@ class MEDIA_EXPORT CoreAudioUtil {
   // Converts between reference time to base::TimeDelta.
   // One reference-time unit is 100 nanoseconds.
   // Example: double s = RefererenceTimeToTimeDelta(t).InMillisecondsF();
-  static base::TimeDelta RefererenceTimeToTimeDelta(REFERENCE_TIME time);
+  static base::TimeDelta ReferenceTimeToTimeDelta(REFERENCE_TIME time);
 
   // Returns AUDCLNT_SHAREMODE_EXCLUSIVE if --enable-exclusive-mode is used
   // as command-line flag and AUDCLNT_SHAREMODE_SHARED otherwise (default).