Initial implementation of Color Pipeline classes.

Design doc:
https://docs.google.com/document/d/1rpNjGg0762tnjfChkA1WJwHalDUQ0ZwkcXsgwwuCuQE/edit?usp=sharing

This implements the core types:
* ColorId
* ColorMixer
* ColorModifier
* ColorProvider
* ColorRecipe
* ColorSet
* ColorSetId
* ColorVariant

It also adds a new "color_unittests" target with unittests that should provide
full coverage of the above, except for ColorVariant (which is not yet used).

Still unimplemented:
* ColorVariant support, including thought about how things like incognito and
  dark mode should work, whether ColorVariant is really the right primitive, and
  whether "inactive" deserves to be a variant.
* A fleshed-out ownership/lifetime model for ColorProfile, which affects what
  constructors or factory functions we expose, as well as the APIs for modifying
  the color pipeline.

This does not include this code anywhere in Chrome.

*.json are autogenerated and do not need review.

Bug: 1003612
Change-Id: I6edf603b407a4cc25315e383974ec0fc0718d9c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1807135
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#698262}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 8d5c4d6132db8f1333ce0e1e0c2a24ae5f9eb74d
diff --git a/test_suite.txt b/test_suite.txt
index 85601bd..39add39 100644
--- a/test_suite.txt
+++ b/test_suite.txt
@@ -17,6 +17,7 @@
 cast_unittests
 cc_unittests
 chrome_app_unittests
+color_unittests
 components_browsertests
 components_unittests
 compositor_unittests