Long line not being broken

Given a file with the following content, I would expect running yapf --style=chromium to split line 7 (the line with the lambda) because it is longer than the line limit (83/80), but it makes no change.

```
def GenTests(api):
success_log_keys = ['test_utils.gtest_results']

yield api.test(
'flake_skipped',
api.post_check(
lambda check, steps: check(steps['test'].logs.keys() == success_log_keys)
),
api.post_process(post_process.DropExpectation),
)
```