android: implement the PermissionAwareActivity interface

This makes the PermissionsAndroid builtin module work.

Introduce the JitsiMeetActivityInterface, which defines the interface that
activities using JitsiMeetView directly must implement in order to ensure full
functionality.

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

@@ -27,6 +27,7 @@ import android.view.KeyEvent;
 
 import com.facebook.react.ReactInstanceManager;
 import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
+import com.facebook.react.modules.core.PermissionListener;
 
 import java.net.URL;
 
@@ -42,7 +43,7 @@ import java.net.URL;
  * {@code JitsiMeetView} static methods.
  */
 public class JitsiMeetActivity
-    extends AppCompatActivity {
+    extends AppCompatActivity implements JitsiMeetActivityInterface {
 
     /**
      * The request code identifying requests for the permission to draw on top
@@ -260,6 +261,15 @@ public class JitsiMeetActivity
         ReactActivityLifecycleCallbacks.onNewIntent(intent);
     }
 
+    // https://developer.android.com/reference/android/support/v4/app/ActivityCompat.OnRequestPermissionsResultCallback
+    @Override
+    public void onRequestPermissionsResult(
+            final int requestCode,
+            final String[] permissions,
+            final int[] grantResults) {
+        ReactActivityLifecycleCallbacks.onRequestPermissionsResult(requestCode, permissions, grantResults);
+    }
+
     @Override
     protected void onResume() {
         super.onResume();
@@ -283,6 +293,14 @@ public class JitsiMeetActivity
         }
     }
 
+    /**
+     * Implementation of the {@code PermissionAwareActivity} interface.
+     */
+    @Override
+    public void requestPermissions(String[] permissions, int requestCode, PermissionListener listener) {
+        ReactActivityLifecycleCallbacks.requestPermissions(this, permissions, requestCode, listener);
+    }
+
     /**
      *
      * @see JitsiMeetView#setDefaultURL(URL)

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

@@ -0,0 +1,15 @@
+package org.jitsi.meet.sdk;
+
+import android.support.v4.app.ActivityCompat;
+
+import com.facebook.react.modules.core.PermissionAwareActivity;
+
+/**
+ * This interface serves as the umbrella interface that applications not using
+ * {@code JitsiMeetActivity} must implement in order to ensure full
+ * functionality.
+ */
+public interface JitsiMeetActivityInterface
+    extends ActivityCompat.OnRequestPermissionsResultCallback,
+            PermissionAwareActivity {
+}

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

@@ -16,11 +16,16 @@
 
 package org.jitsi.meet.sdk;
 
+import android.annotation.TargetApi;
 import android.app.Activity;
 import android.content.Intent;
+import android.os.Build;
 
+import com.calendarevents.CalendarEventsPackage;
 import com.facebook.react.ReactInstanceManager;
+import com.facebook.react.bridge.Callback;
 import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
+import com.facebook.react.modules.core.PermissionListener;
 
 /**
  * Helper class to encapsulate the work which needs to be done on
@@ -28,6 +33,13 @@ import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
  * it.
  */
 public class ReactActivityLifecycleCallbacks {
+    /**
+     * Needed for making sure this class working with the "PermissionsAndroid"
+     * React Native module.
+     */
+    private static PermissionListener permissionListener;
+    private static Callback permissionsCallback;
+
     /**
      * {@link Activity} lifecycle method which should be called from
      * {@link Activity#onBackPressed} so we can do the required internal
@@ -107,6 +119,11 @@ public class ReactActivityLifecycleCallbacks {
         if (reactInstanceManager != null) {
             reactInstanceManager.onHostResume(activity, defaultBackButtonImpl);
         }
+
+        if (permissionsCallback != null) {
+            permissionsCallback.invoke();
+            permissionsCallback = null;
+        }
     }
 
     /**
@@ -126,4 +143,25 @@ public class ReactActivityLifecycleCallbacks {
             reactInstanceManager.onNewIntent(intent);
         }
     }
+
+    public static void onRequestPermissionsResult(
+        final int requestCode,
+        final String[] permissions,
+        final int[] grantResults) {
+        permissionsCallback = new Callback() {
+            @Override
+            public void invoke(Object... args) {
+                if (permissionListener != null
+                        && permissionListener.onRequestPermissionsResult(requestCode, permissions, grantResults)) {
+                    permissionListener = null;
+                }
+            }
+        };
+    }
+
+    @TargetApi(Build.VERSION_CODES.M)
+    public static void requestPermissions(Activity activity, String[] permissions, int requestCode, PermissionListener listener) {
+        permissionListener = listener;
+        activity.requestPermissions(permissions, requestCode);
+    }
 }