Remove presubmit exception for the test runner library

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 37237d9bf62f17973d067332d152361d28908092..46dabb98c4d0cbf2b0e8164520303bc42a62931a 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -28,10 +28,10 @@ _EXCLUDED_PATHS = (
     r"^chrome[\\\/]browser[\\\/]resources[\\\/]pdf[\\\/]index.js"
 )
 
-# TestRunner and NetscapePlugIn library is temporarily excluded from pan-project
-# checks until it's transitioned to chromium coding style.
+# The NetscapePlugIn library is excluded from pan-project as it will soon
+# be deleted together with the rest of the NPAPI and it's not worthwhile to
+# update the coding style until then.
 _TESTRUNNER_PATHS = (
-    r"^content[\\\/]shell[\\\/]renderer[\\\/]test_runner[\\\/].*",
     r"^content[\\\/]shell[\\\/]tools[\\\/]plugin[\\\/].*",
 )