Adds ebuild support to build_autotest

src/scripts/build_autotest.sh

Index: src/scripts/build_autotest.sh
diff --git a/src/scripts/build_autotest.sh b/src/scripts/build_autotest.sh
index 540c3857adf885f717a240e1958f93618b606ee2..59ca8baeed0ce3a8b7094f5a7c1be8d61c70931b 100755
--- a/src/scripts/build_autotest.sh
+++ b/src/scripts/build_autotest.sh
@@ -23,6 +23,8 @@ DEFAULT_CONTROL=client/site_tests/setup/control
 
 DEFINE_string control "${DEFAULT_CONTROL}" \
   "Setup control file -- path relative to the destination autotest directory" c
+DEFINE_string board "" \
+  "Board name for the target you are building if using portage build system"
 
 # More useful help
 FLAGS_HELP="usage: $0 [flags]"
@@ -36,6 +38,13 @@ AUTOTEST_SRC="${GCLIENT_ROOT}/src/third_party/autotest/files"
 # Destination in chroot to install autotest.
 AUTOTEST_DEST="/usr/local/autotest"
 
+# If new build system flag passed, use ebuild and exit
+if [ -n "${FLAGS_board}" ]; then
+  sudo GCLIENT_ROOT="${GCLIENT_ROOT}" FLAGS_control=${FLAGS_control} \
+    "emerge-${FLAGS_board}" -a chromeos-base/autotest
+  exit 0
+fi
+
 # Copy a local "installation" of autotest into the chroot, to avoid
 # polluting the src dir with tmp files, results, etc.
 update_chroot_autotest "${CHROOT_TRUNK_DIR}/src/third_party/autotest/files" \