Reland: Change the video color space default.

Reland: Change the video color space default.

Reverted by: e735fb0c4b13b72561b8f9931a8788e97deced33
Original CL: https://codereview.chromium.org/1228843003
The new change is to media/cast/sender/h264_vt_encoder_unittest.cc.
The rest of the changes are due to rebasing on top of
11edd34b171b78462c1a27ac6587d977833122ea, which moves the color space
enum.

Previously video without color space metadata was assumed to be in
Rec601. Now the default depends on the kind of playback. Normal src=
defaults to Rec601 for SD sized video (<720 pixels high), and Rec709 for
HD. MSE will always default to Rec709. Using a size based heuristic
doesn't make sense for MSE where it is common for the resolution to
change mid playback.

This CL doesn't change the meaning of COLOR_SPACE_UNSPECIFIED. Instead,
it adds a color space field to VideoDecoderConfig, and updates the video
decoders to use this as the default if they don't find a more
authoritative value in the bitstream.

This also fixes a (year old!) bug causing the blackwhite
tests to always succeed, renames the rec709 blackwhite test
file to match the name in blackwhite.html, and re-encodes it
to contain the color space metadata (previously it had none).

BUG=333619
Committed: https://crrev.com/7cb4525761b68e41671af9006920d568be3c5405
Cr-Commit-Position: refs/heads/master@{#338607}

[watk, 2015-07-09 22:35:30]

watk@chromium.org changed reviewers:
+ dalecurtis@chromium.org

[watk, 2015-07-10 21:34:45]

watk@chromium.org changed reviewers:
+ bbudge@chromium.org, gunsch@chromium.org

[watk, 2015-07-10 21:36:44]

PTAL. The previous CL was reverted because it failed to compile an official
build, cast target. I've compiled this new CL locally with the same
configuration.

The only new change over the previous CL is in
media/cast/sender/h264_vt_encoder_unittest.cc

[gunsch, 2015-07-10 21:37:42]

lgtm again (chromecast/)

[bbudge, 2015-07-10 21:41:32]

lgtm

[DaleCurtis, 2015-07-13 02:01:23]

lgtm, typically we upload the original patch as PS#1 and the fixed one as PS#2
when creating a fix for a revert like this.

[watk, 2015-07-13 17:34:31]

On 2015/07/13 02:01:23, DaleCurtis wrote:
> lgtm, typically we upload the original patch as PS#1 and the fixed one as PS#2
> when creating a fix for a revert like this.

Makes sense, thanks.

[watk, 2015-07-13 17:34:38]

The CQ bit was checked by watk@chromium.org

[commit-bot: I haz the power, 2015-07-13 17:35:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1230593005/1

[commit-bot: I haz the power, 2015-07-13 17:38:30]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-13 17:38:31]

Try jobs failed on following builders:
  linux_chromium_compile_dbg_32_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

(exceeded global retry quota)

[watk, 2015-07-13 21:13:09]

The CQ bit was checked by watk@chromium.org

[watk, 2015-07-13 21:13:09]

The patchset sent to the CQ was uploaded after l-g-t-m from bbudge@chromium.org,
dalecurtis@chromium.org, gunsch@chromium.org
Link to the patchset: https://codereview.chromium.org/1230593005/#ps20001
(title: "big rebase")

[watk, 2015-07-13 21:13:16]

The CQ bit was unchecked by watk@chromium.org

[watk, 2015-07-14 00:09:27]

The CQ bit was checked by watk@chromium.org

[commit-bot: I haz the power, 2015-07-14 00:09:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1230593005/20001

[commit-bot: I haz the power, 2015-07-14 00:46:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-14 00:47:28]

Patchset 2 (id:??) landed as
https://crrev.com/7cb4525761b68e41671af9006920d568be3c5405
Cr-Commit-Position: refs/heads/master@{#338607}