Reland linux_aura: Implement most of DesktopScreenX11.

Reland linux_aura: Implement most of DesktopScreenX11.

[[Making changes to '_toolset=="target"' section in system.gyp to fix
cros compiling.]]

The linux_aura port didn't deal with multiple monitors very well because
it was treating the X root window as one big display. When xrandr is
present, get the screen areas from it, and exposes this data back to
chrome.

This patch also factors out the EDID parser than chromeos was using into
a common directory. Like chromeos, we use it to assign stable display
IDs.

BUG=287972
TBR=brettw@chromium.org, derat@chromium.org, sky@chromium.org
First Review URL: https://codereview.chromium.org/23536057

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=225254

[Elliot Glaysher, 2013-09-25 03:17:28]

(recommitting. only change is some minor changes to the gyp files to make
cros_x86 happy. this is a tbr.)

[commit-bot: I haz the power, 2013-09-25 03:18:43]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/erg@chromium.org/24459002/3001

[commit-bot: I haz the power, 2013-09-25 05:07:13]

Retried try job too often on linux_rel for step(s) remoting_unittests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[Elliot Glaysher, 2013-09-25 21:32:26]

Committed patchset #2 manually as r225254 (presubmit successful).