Move code out of supported_cdm_versions.h

In the future there will be additional code that use the functions in
supported_cdm_versions.h. To avoid duplicate definitions, move it into
a separate .cc file.

TEST=compiles

Review URL: https://codereview.chromium.org/1430503004

Cr-Commit-Position: refs/heads/master@{#357726}
5 files changed