Make global blocked_terms.txt default for search_blocked_terms.sh

Currently, search_blocked_terms.sh reads words from the local
unblocked_terms.txt, in which words may have been accidentally removed.

This change makes search_blocked_terms.sh read words from the global
blocked_terms.txt by default.

BUG=b:165908442
TEST=Run search_blocked_terms.sh with/without argument.

Change-Id: Id6949eeeafd4528fe03f3bcb6fad78b24e852b0b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2410558
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
diff --git a/contrib/search_blocked_words.sh b/contrib/search_blocked_words.sh
index 6057139..cbc0ada 100755
--- a/contrib/search_blocked_words.sh
+++ b/contrib/search_blocked_words.sh
@@ -8,25 +8,18 @@
 #
 # Usage: search_blocked_words.sh [/path/to/word_list.txt]
 #
-# Use case 1: Search all globally blocked words.
-#
-#   $ search_blocked_words.sh ~/trunk/src/repohooks/blocked_terms.txt
-#
-# - This is useful when first introducing unblocked_terms.txt to a repo.
-# - This is also useful to verify the blocked words indeed do not exist.
-#   Some CLs may have checked in blocked words using '--no-verify' flag
-#   circumventing the repo check.
-#
-# Use case 2: Search all words in the local unblock list.
+# You can search the current directory for globally blocked words:
 #
 #   $ search_blocked_words.sh
 #
-# - This is useful to learn the current COIL status.
+# You can pass the project's unblocked_terms.txt to narrow the search scope:
+#
+#   $ search_blocked_words.sh ./unblocked_terms.txt
 
-input_file=${1:-unblocked_terms.txt}
+input_file=${1:-~/trunk/src/repohooks/blocked_terms.txt}
 if [[ ! -r "${input_file}" ]]; then
   echo "Error: '${input_file}' not found."
-  echo "Have you copied repohooks/unblocked_terms.txt?"
+  echo "This script is expected to run in CrOS SDK chroot."
   echo "Read repohooks/README.md for more information."
   exit 1
 fi