Native android service implemented

client/android/src/org/amnezia/vpn/qt/VPNActivity.java

@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.amnezia.vpn.qt;
+
+import android.view.KeyEvent;
+
+public class VPNActivity extends org.qtproject.qt5.android.bindings.QtActivity {
+
+  @Override
+  public boolean onKeyDown(int keyCode, KeyEvent event) {
+    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
+      onBackPressed();
+      return true;
+    }
+    return super.onKeyDown(keyCode, event);
+  }
+
+  @Override
+  public void onBackPressed() {
+    try {
+      if (!handleBackButton()) {
+        // Move the activity into paused state if back button was pressed
+        moveTaskToBack(true);
+      }
+    } catch (Exception e) {
+    }
+  }
+
+  // Returns true if MVPN has handled the back button
+  native boolean handleBackButton();
+}