cros-unibuild: Add unibuild_install_touch_workdir

Add a version of unibuild_install_touch_files which pulls from $WORKDIR..
This is where CPFE files are placed using cros-binary_add_gs_uri.

BUG=b:175749947
TEST=Verify both unibuild_install_touch_files/workdir

Change-Id: Ia808a203dfcfa83c21fe97c3b24e8d9ee12325f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/2594191
Tested-by: Bob Moragues <moragues@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: C Shapiro <shapiroc@chromium.org>
diff --git a/eclass/cros-unibuild.eclass b/eclass/cros-unibuild.eclass
index e1d81c3..560a30a 100644
--- a/eclass/cros-unibuild.eclass
+++ b/eclass/cros-unibuild.eclass
@@ -265,11 +265,18 @@
 	local cmd="$1"
 	local files_path="${FILESDIR}"
 	local config="${SYSROOT}${UNIBOARD_YAML_DIR}/config.yaml"
+
 	if [[ $# -gt 1 ]]; then
 		files_path="."
 		config="$2"
 	fi
 
+	# Determine if using files or workdir for the path.
+	if [[ "${cmd}" == "get-touch-firmware-workdir" ]]; then
+		cmd="get-touch-firmware-files"
+		files_path="${WORKDIR}"
+	fi
+
 	einfo "unibuild: Installing ${cmd} based on ${config}"
 	set -o pipefail
 	cros_config_host -c "${config}" "${cmd}" |
@@ -284,7 +291,7 @@
 # @USAGE: [config_file]
 # @DESCRIPTION:
 # Install files related to touch firmware. This includes firmware for the
-# touchscreen, touchpad and stylus.
+# touchscreen, touchpad and stylus.  These files are expected in files dir.
 # Args:
 #   $1: (optional) Config file used by cros_config_host
 unibuild_install_touch_files() {
@@ -292,6 +299,18 @@
 	_unibuild_install_fw_common "get-touch-firmware-files" "$@"
 }
 
+# @FUNCTION: unibuild_install_touch_workdir
+# @USAGE: [config_file]
+# @DESCRIPTION:
+# Install files related to touch firmware. This includes firmware for the
+# touchscreen, touchpad and stylus. These files are expected in work dir.
+# Args:
+#   $1: (optional) Config file used by cros_config_host
+unibuild_install_touch_workdir() {
+	[[ $# -lt 2 ]] || die "${FUNCNAME}: Only optional config file arg allowed"
+	_unibuild_install_fw_common "get-touch-firmware-workdir" "$@"
+}
+
 # @FUNCTION: unibuild_install_detachable_base_files
 # @USAGE: [config_file]
 # @DESCRIPTION: