GitLab

Adds cdm_type_converters.{h,cc} which collects all type converters
between cdm:: and media:: types.

Some conversion functions are renamed for consistency.

Bug: 707128
Test: No functionality change.
Change-Id: I0ac755f8820d4cf719f3b2c6c6885ec21f45f129
Reviewed-on: https://chromium-review.googlesource.com/c/1260488
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597347}