Rename page-popup helper functions.

- openPicker() -> openPickerWithMock()
- openPickerWithoutMock() -> openPicker().

BUG=409503

Review URL: https://codereview.chromium.org/618193003

git-svn-id: svn://svn.chromium.org/blink/trunk@183175 bbb929c8-8fbe-4397-9dbb-9b2b20218538