Request dismissing keyguard when showing MediaProjection Dialog

If the MediaProjection Dialog is about to show on top of keyguard,
instead requets the user to unlock their device first.

Bug: 351409536
Test: manual + presubmit
Flag: com.android.systemui.media_projection_dialog_behind_lockscreen
Change-Id: I45867660f88a2a59c16b95126d776ad8d3d88b35
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index 98c491b..e6c68f9 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -1408,3 +1408,13 @@
    description: "Allow non-touchscreen devices to bypass falsing"
    bug: "319809270"
 }
+
+flag {
+   name: "media_projection_dialog_behind_lockscreen"
+   namespace: "systemui"
+   description: "Ensure MediaProjection Dialog appears behind the lockscreen"
+   bug: "351409536"
+   metadata {
+       purpose: PURPOSE_BUGFIX
+   }
+}
\ No newline at end of file