SurfaceControl: Add setDropInputMode api

Introduces an API to drop input events on this SurfaceControl. This
policy will be inherited by its children. The caller must hold the
ACCESS_SURFACE_FLINGER permission.

Options include:
ALL: SurfaceControl and its children will not receive any
input regardless of whether it has a valid input channel.
OBSCURED: SurfaceControl and its children will not
receive any input if the layer is obscured, cropped by its parent or
translucent.

These policies are used to enable features that allow for a less trusted
interaction model between apps. See the bug for more details.

Test: atest libgui_test InputDispatcherDropInputFeatureTest
Bug:197364677

Change-Id: I443741d5ab51a45d37fb865f11c433c436d96c1e
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 3c3c7d0..b70d5d4 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -17,6 +17,7 @@
 
 #pragma once
 
+#include <android/gui/DropInputMode.h>
 #include <compositionengine/LayerFE.h>
 #include <gui/BufferQueue.h>
 #include <gui/ISurfaceComposerClient.h>
@@ -277,6 +278,8 @@
         Rect destinationFrame;
 
         sp<IBinder> releaseBufferEndpoint;
+
+        gui::DropInputMode dropInputMode;
     };
 
     /*
@@ -442,6 +445,8 @@
     virtual bool setFrameRateSelectionPriority(int32_t priority);
     virtual bool setFixedTransformHint(ui::Transform::RotationFlags fixedTransformHint);
     virtual void setAutoRefresh(bool /* autoRefresh */) {}
+    bool setDropInputMode(gui::DropInputMode);
+
     //  If the variable is not set on the layer, it traverses up the tree to inherit the frame
     //  rate priority from its parent.
     virtual int32_t getFrameRateSelectionPriority() const;