Gate support for certain EOTFs/primaries/matrices on color management / hdr flags

Creates a new class VideoColorSpace specifically for encoding color spaces
according to ISO/IEC 23001-8.

Plumb this color space through from parsing to validation.

BUG=687627

Review-Url: https://codereview.chromium.org/2742113002
Cr-Commit-Position: refs/heads/master@{#456518}
void MimeUtil::RemoveProprietaryMediaTypesAndCodecs() {
  for (const auto& container : proprietary_media_containers_)
    media_format_map_.erase(container);
  allow_proprietary_codecs_ = false;
}

void MimeUtil::RemoveProprietaryMediaTypesAndCodecs() {
  for (const auto& container : proprietary_media_containers_)
    media_format_map_.erase(container);
  allow_proprietary_codecs_ = false;
}
