Mirror "secure" content

Some applications, like Silence, prevent the content of a window from
being viewed on non-secure displays:
<https://developer.android.com/reference/android/view/WindowManager.LayoutParams.html#FLAG_SECURE>

We can mirror it by just creating a "secure" display:
<https://developer.android.com/reference/android/view/Display#FLAG_SECURE>

FAQ.md

@@ -24,20 +24,6 @@ If you still encounter problems, please see [issue 9].
 [issue 9]: https://github.com/Genymobile/scrcpy/issues/9
 
 
-### I get a black screen for some applications like Silence
-
-This is expected, they requested to [protect] the screen.
-
-In [Silence], you can disable it in settings → Privacy → Screen security.
-
-[protect]: https://developer.android.com/reference/android/view/Display#FLAG_SECURE
-[silence]: https://f-droid.org/en/packages/org.smssecure.smssecure/
-
-See [issue 36].
-
-[issue 36]: https://github.com/Genymobile/scrcpy/issues/36
-
-
 ### Mouse clicks do not work
 
 On some devices, you may need to enable an option to allow [simulating input].

server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java

@@ -151,7 +151,7 @@ public class ScreenEncoder implements Device.RotationListener {
     }
 
     private static IBinder createDisplay() {
-        return SurfaceControl.createDisplay("scrcpy", false);
+        return SurfaceControl.createDisplay("scrcpy", true);
     }
 
     private static void configure(MediaCodec codec, MediaFormat format) {