I'm wondering if we should switch to libwebm parser in Chromium instead of adding Colour element support to the existing webm parser under media/formats/webm. Sent out an e-mail to start a discussion.

After some further discussion with fgalligan@ we've decided that for now it's easier to add the support for reading Colour element in the current WebM parser, rather that switch to libwebm.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b51b4c09996725907fec2f9436d0c36cadd0d0c2

commit b51b4c09996725907fec2f9436d0c36cadd0d0c2
Author: servolk <servolk@chromium.org>
Date: Sat Sep 17 01:06:42 2016

Support ARIB STD B67, aka hybrid-log gamma (HLG) transfer function.

BUG= 645626 

Review-Url: https://codereview.chromium.org/2342963003
Cr-Commit-Position: refs/heads/master@{#419357}

[modify] https://crrev.com/b51b4c09996725907fec2f9436d0c36cadd0d0c2/ui/gfx/color_space.h
[modify] https://crrev.com/b51b4c09996725907fec2f9436d0c36cadd0d0c2/ui/gfx/color_transform.cc
[modify] https://crrev.com/b51b4c09996725907fec2f9436d0c36cadd0d0c2/ui/gfx/color_transform_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3

commit e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3
Author: servolk <servolk@chromium.org>
Date: Fri Sep 23 00:52:58 2016

Add color metadata info to VideoDecoderConfig.

Also implemented reading color metadata from the Colour element in WebM containers.

BUG= 645626 

Review-Url: https://codereview.chromium.org/2333663003
Cr-Commit-Position: refs/heads/master@{#420511}

[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/BUILD.gn
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/base/BUILD.gn
[add] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/base/hdr_metadata.cc
[add] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/base/hdr_metadata.h
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/base/video_decoder_config.cc
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/base/video_decoder_config.h
[add] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/formats/webm/webm_colour_parser.cc
[add] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/formats/webm/webm_colour_parser.h
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/formats/webm/webm_constants.h
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/formats/webm/webm_parser.cc
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/formats/webm/webm_stream_parser_unittest.cc
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/formats/webm/webm_video_client.cc
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/formats/webm/webm_video_client.h
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/test/data/README
[add] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/media/test/data/colour.webm
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/ui/gfx/color_space.h
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/ui/gfx/color_transform.cc
[modify] https://crrev.com/e21ae6e132cd646d0fc8f3aeda071e0d2e5bc4f3/ui/gfx/color_transform_unittest.cc