android: simplify the creation of AudioManager

Do so on the main thread at startup and pass it along.

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioDeviceHandlerConnectionService.java

      */
     private int supportedRouteMask = -1;
 
-    public AudioDeviceHandlerConnectionService() {
+    public AudioDeviceHandlerConnectionService(AudioManager audioManager) {
+        this.audioManager = audioManager;
     }
 
     @Override
     }
 
     @Override
-    public void start(Context context, AudioModeModule audioModeModule) {
+    public void start(AudioModeModule audioModeModule) {
         JitsiMeetLogger.i("Using " + TAG + " as the audio device handler");
 
         module = audioModeModule;
-        audioManager = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);
 
         RNConnectionService rcs = ReactInstanceManagerHolder.getNativeModule(RNConnectionService.class);
         if (rcs != null) {

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioDeviceHandlerGeneric.java

             }
         };
 
-    public AudioDeviceHandlerGeneric() {
+    public AudioDeviceHandlerGeneric(AudioManager audioManager) {
+        this.audioManager = audioManager;
     }
 
     /**
     }
 
     @Override
-    public void start(Context context, AudioModeModule audioModeModule) {
+    public void start(AudioModeModule audioModeModule) {
         JitsiMeetLogger.i("Using " + TAG + " as the audio device handler");
 
         module = audioModeModule;
-        audioManager = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);
 
         // Setup runtime device change detection.
         audioManager.registerAudioDeviceCallback(audioDeviceCallback, null);

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioDeviceHandlerLegacy.java

      */
     private BluetoothHeadsetMonitor bluetoothHeadsetMonitor;
 
-    public AudioDeviceHandlerLegacy() {
+    public AudioDeviceHandlerLegacy(AudioManager audioManager) {
+        this.audioManager = audioManager;
     }
 
     /**
     }
 
     @Override
-    public void start(Context context, AudioModeModule audioModeModule) {
+    public void start(AudioModeModule audioModeModule) {
         JitsiMeetLogger.i("Using " + TAG + " as the audio device handler");
 
         module = audioModeModule;
-        audioManager = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);
+        Context context = module.getContext();
 
         // Setup runtime device change detection.
         //

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioModeModule.java

 package org.jitsi.meet.sdk;
 
 import android.content.Context;
+import android.media.AudioManager;
 import android.os.Build;
 
 import com.facebook.react.bridge.Arguments;
         return supportsConnectionService && useConnectionService_;
     }
 
+    /**
+     * {@link AudioManager} instance used to interact with the Android audio
+     * subsystem.
+     */
+    private AudioManager audioManager;
+
     private AudioDeviceHandlerInterface audioDeviceHandler;
 
     /**
      */
     public AudioModeModule(ReactApplicationContext reactContext) {
         super(reactContext);
+
+        audioManager = (AudioManager)reactContext.getSystemService(Context.AUDIO_SERVICE);
     }
 
     /**
         }
 
         if (useConnectionService()) {
-            audioDeviceHandler = new AudioDeviceHandlerConnectionService();
+            audioDeviceHandler = new AudioDeviceHandlerConnectionService(audioManager);
         } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-            audioDeviceHandler = new AudioDeviceHandlerGeneric();
+            audioDeviceHandler = new AudioDeviceHandlerGeneric(audioManager);
         } else {
-            audioDeviceHandler = new AudioDeviceHandlerLegacy();
+            audioDeviceHandler = new AudioDeviceHandlerLegacy(audioManager);
         }
 
-        audioDeviceHandler.start(getReactApplicationContext(), this);
+        audioDeviceHandler.start(this);
     }
 
     /**
         }
     }
 
+    /**
+     * Needed on the legacy handler...
+     *
+     * @return Context for the application.
+     */
+    Context getContext() {
+        return getReactApplicationContext();
+    }
+
     /**
      * Interface for the modules implementing the actual audio device management.
      */
     interface AudioDeviceHandlerInterface {
         /**
          * Start detecting audio device changes.
-         * @param context Android {@link Context} where detection should take place.
          * @param audioModeModule Reference to the main {@link AudioModeModule}.
          */
-        void start(Context context, AudioModeModule audioModeModule);
+        void start(AudioModeModule audioModeModule);
 
         /**
          * Stop audio device detection.