Implement CdmFileIO in CdmAdapter.

R=ddorwin@chromium.org
TBR=ddorwin@chromium.org
BUG=324134
TEST=Tests will follow in another CL. All tests cases pass with that test.

Review URL: https://codereview.chromium.org/103853005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241176 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241177 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241177