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.

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

Note: this backport does not include the OBSCURED option since its
not needed for the security fix.

Test: atest libgui_test InputDispatcherDropInputFeatureTest
Bug: 197296414

Merged-In: I443741d5ab51a45d37fb865f11c433c436d96c1e
Change-Id: I443741d5ab51a45d37fb865f11c433c436d96c1e
diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index a897d10..dfcef8f 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -118,7 +118,7 @@
     output.writeByte(frameRateCompatibility);
     output.writeUint32(fixedTransformHint);
     output.writeBool(isTrustedOverlay);
-
+    output.writeUint32(static_cast<uint32_t>(dropInputMode));
     return NO_ERROR;
 }
 
@@ -204,6 +204,9 @@
     fixedTransformHint = static_cast<ui::Transform::RotationFlags>(input.readUint32());
     isTrustedOverlay = input.readBool();
 
+    uint32_t mode;
+    mode = input.readUint32();
+    dropInputMode = static_cast<gui::DropInputMode>(mode);
     return NO_ERROR;
 }
 
@@ -447,6 +450,10 @@
         what |= eTrustedOverlayChanged;
         isTrustedOverlay = other.isTrustedOverlay;
     }
+    if (other.what & eDropInputModeChanged) {
+        what |= eDropInputModeChanged;
+        dropInputMode = other.dropInputMode;
+    }
     if ((other.what & what) != other.what) {
         ALOGE("Unmerged SurfaceComposer Transaction properties. LayerState::merge needs updating? "
               "other.what=0x%" PRIu64 " what=0x%" PRIu64,