Make lint errors fatal in presubmit and fix files in whitelisted paths

BUG=webrtc:5149

Review-Url: https://codereview.webrtc.org/2762963002
Cr-Commit-Position: refs/heads/master@{#17323}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 72e4326..03a77b2 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -255,9 +255,7 @@
 
   if cpplint._cpplint_state.error_count > 0:
     if input_api.is_committing:
-      # TODO(kjellander): Change back to PresubmitError below when we're
-      # confident with the lint settings.
-      res_type = output_api.PresubmitPromptWarning
+      res_type = output_api.PresubmitError
     else:
       res_type = output_api.PresubmitPromptWarning
     result = [res_type('Changelist failed cpplint.py check.')]