SurfaceFlinger: Implement drop input modes

ALL: If this mode is set on a layer, set the DROP_INPUT
feature flag on the layer and its children if it has a valid input
channel. This will ensure these layers will not be able to receive any
input.

OBSCURED: If this mode is set, set the DROP_INPUT
feature flag on the layer and its children if they have a valid input
channel and they are considered occluded. This can happen if the layer
has a alpha set by it's parent OR if its buffer has been cropped by its
parent. Otherwise, the input feature flag DROP_INPUT_IF_OBSCURED flag
will be set so inputflinger can decide to drop input based on
occlusion.

Test: atest libgui_test InputDispatcherDropInputFeatureTest
Bug: 197364677
Merged-In: Ibce11ee7df5b5c8c226ebfab29574a99cd656f6d
Change-Id: Ibce11ee7df5b5c8c226ebfab29574a99cd656f6d
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index dda94b2..b107f8e 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -1062,6 +1062,8 @@
     bool setFrameRateForLayerTree(FrameRate);
     void setZOrderRelativeOf(const wp<Layer>& relativeOf);
     bool isTrustedOverlay() const;
+    gui::DropInputMode getDropInputMode() const;
+    void handleDropInputMode(gui::WindowInfo& info) const;
 
     // Find the root of the cloned hierarchy, this means the first non cloned parent.
     // This will return null if first non cloned parent is not found.