Improve handling of DEPS OWNERS PRESUBMIT check

BUG=593533

Review URL: https://codereview.chromium.org/2120283002 .

Cr-Commit-Position: refs/heads/master@{#403680}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 134f62de..1a3c40c 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -1097,13 +1097,13 @@
 
   if unapproved_dependencies:
     output_list = [
-      output('Missing LGTM from OWNERS of dependencies added to DEPS:\n    %s' %
-             '\n    '.join(sorted(unapproved_dependencies)))]
-    if not input_api.is_committing:
-      suggested_owners = owners_db.reviewers_for(missing_files, owner_email)
-      output_list.append(output(
-          'Suggested missing target path OWNERS:\n    %s' %
-          '\n    '.join(suggested_owners or [])))
+      output('You need LGTM from owners of depends-on paths in DEPS that were '
+             'modified in this CL:\n    %s' %
+                 '\n    '.join(sorted(unapproved_dependencies)))]
+    suggested_owners = owners_db.reviewers_for(missing_files, owner_email)
+    output_list.append(output(
+        'Suggested missing target path OWNERS:\n    %s' %
+            '\n    '.join(suggested_owners or [])))
     return output_list
 
   return []