Adds changes to unittest scripts to use ebuild if board is specified

src/scripts/build_tests.sh

Index: src/scripts/build_tests.sh
diff --git a/src/scripts/build_tests.sh b/src/scripts/build_tests.sh
index a057b60e673060a3c96fb370a1bf92004a9574f2..895c5e572f8d8242eba3dd9c52781b17d5c5e1a6 100755
--- a/src/scripts/build_tests.sh
+++ b/src/scripts/build_tests.sh
@@ -12,6 +12,9 @@ assert_inside_chroot
 assert_not_root_user
 
 # Flags
+DEFINE_string build_root "$DEFAULT_BUILD_ROOT"                \
+  "Root of build output"
+DEFINE_string board "" "Target board for which tests are to be built"
 
 # Parse command line
 FLAGS "$@" || exit 1
@@ -20,16 +23,23 @@ eval set -- "${FLAGS_ARGV}"
 # Die on error; print commands
 set -e
 
-PLATFORM_DIR="$SRC_ROOT/platform"
-PLATFORM_DIRS="pam_google window_manager cryptohome"
-
-# Build tests
-for i in $PLATFORM_DIRS
-do
-  echo "building $PLATFORM_DIR/$i"
-  cd "$PLATFORM_DIR/$i"
-  ./make_tests.sh
-  cd -
-done
-
-echo "All tests built."
+TEST_DIRS="pam_google window_manager cryptohome"
+
+if [ -n "$FLAGS_board" ]
+then  
+  sudo TEST_DIRS="${TEST_DIRS}" \
+    emerge-${FLAGS_board} chromeos-base/chromeos-unittests
+else 
+  PLATFORM_DIR="$SRC_ROOT/platform"  
+  
+  # Build tests
+  for i in ${TEST_DIRS}
+  do
+    echo "building $PLATFORM_DIR/$i"
+    cd "$PLATFORM_DIR/$i"
+    OUT_DIR="${FLAGS_build_root}/x86/tests" ./make_tests.sh
+    cd -
+  done
+
+  echo "All tests built."
+fi