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}
  TestContentRendererClient() : is_extra_key_system_enabled_(false) {}

  TestContentRendererClient() : is_extra_key_system_enabled_(false) {}
