media: Remove MojoCdmProxy::Destroy()

As a result of CDM_10 interface change to simplify things.
- Remove CdmProxy::Destroy().
- Rename CreateCdmProxy() to RequestCdmProxy().
- Use CdmProxy::Protocol::kNone for failure and test cases.

BUG=803710
TEST=Fix existing tests

Change-Id: I073cfc16888158b0aa841b8c78b7c9158ba29445
Reviewed-on: https://chromium-review.googlesource.com/912608
Reviewed-by: Xiaohan Wang <[email protected]>
Reviewed-by: Frank Liberato <[email protected]>
Commit-Queue: Xiaohan Wang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#536505}
12 files changed