media: Add MojoCdmFactory and enable mojo CDM creation.
- Add MojoCdmFactory, the CdmFactory that supports MojoCdm.
- Add Initialize() call on the mojo ContentDecryptionModule interface. This call
takes a callback, so that we can make sure the remote CDM is successfully
created. This is similar to what we are doing in ProxyMediaKeys.
- MojoCdmService is owned by the pipe instead of by the "context". This looks
more natural and simplifies many code.
TBR=ddorwin@chromium.org
BUG=432998
TEST=Manually tested with the next CL on a local test page that uses Clear Key
key system.
Review URL: https://codereview.chromium.org/
1188153002
Cr-Commit-Position: refs/heads/master@{#335642}