Ensure the plugin's native code is never called with an invalid NPP pointer.
diff --git a/samples/BrowserPlugin/jni/PluginObject.h b/samples/BrowserPlugin/jni/PluginObject.h
index 21b7707..691234f 100644
--- a/samples/BrowserPlugin/jni/PluginObject.h
+++ b/samples/BrowserPlugin/jni/PluginObject.h
@@ -61,6 +61,10 @@
     virtual void surfaceCreated(jobject) = 0;
     virtual void surfaceChanged(int format, int width, int height) = 0;
     virtual void surfaceDestroyed() = 0;
+
+    void setJavaInterface(jobject);
+
+    jobject m_javaInterface;
 };
 
 enum PluginTypes {