update article

Author: NickIliev

docs/core-concepts/android-runtime/advanced-topics/extend-application-activity.md

@@ -108,6 +108,9 @@ The core modules ship with a default `android.support.v7.app.AppCompatActivity`
     const superProto = android.support.v7.app.AppCompatActivity.prototype;
     android.support.v7.app.AppCompatActivity.extend("org.myApp.MainActivity", {
         onCreate: function(savedInstanceState) {
+            // Set the isNativeScriptActivity in onCreate (as done in the original NativeScript activity code)
+            // The JS constructor might not be called because the activity is created from Android.
+            this.isNativeScriptActivity = true;
             if(!this._callbacks) {
                 frame.setActivityCallbacks(this);
             }
@@ -144,9 +147,14 @@ The core modules ship with a default `android.support.v7.app.AppCompatActivity`
 
     @JavaProxy("org.myApp.MainActivity")
     class Activity extends android.support.v7.app.AppCompatActivity {
+        public isNativeScriptActivity;
+
         private _callbacks: AndroidActivityCallbacks;
         
         public onCreate(savedInstanceState: android.os.Bundle): void {
+            // Set the isNativeScriptActivity in onCreate (as done in the original NativeScript activity code)
+            // The JS constructor might not be called because the activity is created from Android.
+            this.isNativeScriptActivity = true;
             if (!this._callbacks) {
                 setActivityCallbacks(this);
             }