Sample rate 0 means a route-dependent rate

Remove check for primary _output_ [sic] sampling rate for fast capture.
Clean up AudioRecord handling of frame count and sample rate.
Clean up AudioTrack handling of notification period updates.
Make AudioRecord and AudioTrack more similar in order of operation, comments, and whitespace.

Bug: 25641253
Bug: 21019153
Change-Id: I24a6677945987fc39a9bf93f70357e4bc7410f98
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 273cfe1..fb1ece4 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -564,6 +564,7 @@
                                      PlaybackThread *srcThread,
                                      PlaybackThread *dstThread,
                                      bool reRegister);
+
               // return thread associated with primary hardware device, or NULL
               PlaybackThread *primaryPlaybackThread_l() const;
               audio_devices_t primaryOutputDevice_l() const;