Add IAudioManager methods for tracking client recording activity

audio_unique_id_t IAudioManager::trackRecorder(IBinder token)
  - registers a client recorder withing Audio Service,
    returns a unique tracking recording ID (RIID);
    Audio Service tracks the lifetime of the recorder using
    the provided token.

oneway recorderEvent(int riid, int event)
  - updates the current state of the client;
    only "started" and "stoped" states are considered.

Bug: 123312504
Test: android.media.cts.AudioRecordingConfigurationTest
      AudioRecordTest#testAudioRecordInfoCallback
      MediaRecorderTest#testAudioRecordInfoCallback
      manual testing using Oboe and Solo test apps

Change-Id: Iddb1b91fff7127ab35ba1d33e3e6c32937ac3081
diff --git a/include/audiomanager/AudioManager.h b/include/audiomanager/AudioManager.h
index 009dc52..639df7a 100644
--- a/include/audiomanager/AudioManager.h
+++ b/include/audiomanager/AudioManager.h
@@ -20,7 +20,6 @@
 namespace android {
 
 // must be kept in sync with definitions in AudioPlaybackConfiguration.java
-
 #define PLAYER_PIID_INVALID -1
 
 typedef enum {
@@ -40,6 +39,15 @@
     PLAYER_STATE_STOPPED  = 4,
 } player_state_t;
 
+// must be kept in sync with definitions in AudioManager.java
+#define RECORD_RIID_INVALID -1
+
+typedef enum {
+    RECORDER_STATE_UNKNOWN  = -1,
+    RECORDER_STATE_STARTED  = 0,
+    RECORDER_STATE_STOPPED  = 1,
+} recorder_state_t;
+
 }; // namespace android
 
 #endif // ANDROID_AUDIOMANAGER_H