Remove support for custom overscroll background

Mac was the only platform to do this, and more recent versions
of the OS do not support it anymore. Callers to these functions
have been removed from the Blink side.

BUG=248742

Review URL: https://codereview.chromium.org/838603002

Cr-Commit-Position: refs/heads/master@{#312529}


CrOS-Libchrome-Original-Commit: cbcd8ee26310f2e9a3be4395362a9be1c490c897
2 files changed
tree: 9bd4cc6bb5b17ed5e569fac21dff42dac3e6bba3
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/