AudioFlinger: enforce OP_RECORD_AUDIO during recording

  Fix issue where RecordTrack silencing didn't silence the
full buffer: the memset to 0 was using the RecordThread frame
size, not the RecordTrack frame size.
  OP_RECORD_AUDIO was only enforced at the start of a recording
which would fail if not granted. This patch silences the recording
(i.e. silence is recorded instead) when it is lost, and undoes that
when granted again. This requires:
- propagating the package name of the client to the RecordTrack class
- registering an appOp callback in RecordTrack (through a new
  OpRecordAudioMonitor class) to (un)silence the recording
- update the isSilenced() method to take into account the appOp.

Bug: 138968594
Test: run app that records audio, then "adb shell appops __pack_name__ 27 2"
     and verify recording is silent after that.

Change-Id: Ib33f5b592185a67204997213bab1ac2594d90d37
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index fc8aa13..87bebf3 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -1553,7 +1553,8 @@
                     audio_input_flags_t *flags,
                     pid_t tid,
                     status_t *status /*non-NULL*/,
-                    audio_port_handle_t portId);
+                    audio_port_handle_t portId,
+                    const String16& opPackageName);
 
             status_t    start(RecordTrack* recordTrack,
                               AudioSystem::sync_event_t event,