For the H264 video codec, comparing the codec name is not enough
for determining a match. The profile-level-id must also match.
This CL:
- Specializes the VideoCodec::Matches function with extra logic for
matching H264 codecs.
- Adds unittests for matching H264 video codecs.
- Removes the unnecessary CodecTest fixture class.
BUG=webrtc:6337,chromium:645599
Review-Url: https://codereview.webrtc.org/2347863003
Cr-Commit-Position: refs/heads/master@{#14546}