Make magnification ignore invisible wallpaper.

Magnification was assuming that all windows for which
isOnScreen() returned true were visible, but that is not
true for at least wallpapers that have been made invisible.
Adding a check for visibility in addition to on screen.

Bug: 7215285
Change-Id: Iadea37c9eec981f1d68c5a42959debb58cbab264

services/core/java/com/android/server/wm/AccessibilityController.java

@@ -644,7 +644,7 @@ final class AccessibilityController {
                 final int windowCount = windowList.size();
                 for (int i = 0; i < windowCount; i++) {
                     WindowState windowState = windowList.get(i);
-                    if (windowState.isOnScreen() &&
+                    if (windowState.isOnScreen() && windowState.isVisibleLw() &&
                             !windowState.mWinAnimator.mEnterAnimationPending) {
                         outWindows.put(windowState.mLayer, windowState);
                     }