GN build: GPU work, Windows compile, "check" errors

GN build: GPU work, Windows compile, "check" errors

Fix the "gn check" header errors.

Remove the extra "gles2_utils" target which "gn check" flags as an error. This target is actually inseparable from "command_buffer_common" but exists this way to prevent cycles in GYP files (but not GYP targets). GN doesn't have this problem, so I merged them.

Moved the GPU targets out into build files closer to their files (gpu/command_buffer/client and .../common). This leaves a BUILD.gn file in gpu/ with a comment listing the forwarding locations, since that's where people will look for a BUILD.gn file first.

Delete the duplicate gfx_unittests target, leave a comment for where it is in case somebody does a search for that name.

Make webp compile on Windows

Make ui/gfx compile on Windows. There were some duplicate symbols for ozone. I changed some of the filtering around to do += instead of exclusion. I think in these cases it's easier to follow and maintain.

BUG=
R=piman@chromium.org, urvang@google.com

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=271080

[urvang (Google), 2014-05-16 17:58:02]

LGTM for WebP

[piman, 2014-05-16 18:44:04]

lgtm

[brettw, 2014-05-16 19:34:37]

Committed patchset #4 manually as r271080.