chromeos: Move some network related UI in ui/chromeos/

chromeos: Move some network related UI in ui/chromeos/

Move the code responsible for showing network icons into a common component
so that it can be used from both ash and athena. This also moves the relevant
string and image-resources out of ash into separate ui_chromeos_ targets.

R=mmoss@chromium.org, oshima@chromium.org, sky@chromium.org, stevenjb@chromium.org
TBR=derat@ for third_party/cros_system_api owners
BUG=387199
Previously landed in r282837, and reverted in r282839 because it broke non-chromeos builds.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=282858

[stevenjb, 2014-07-02 17:56:20]

lgtm
cc:jennyz@ FYI

[oshima, 2014-07-08 18:35:28]

lgtm

[sadrul, 2014-07-10 13:18:40]

mmoss@chromium.org: Please review changes in chrome/tools/

[Michael Moss, 2014-07-10 15:22:58]

lgtm

[sadrul, 2014-07-10 16:40:06]

+sky@ for chrome/chrome_resources.gyp,
chrome/tools/check_grd_for_unused_strings.py, and 
chrome/browser/ui/webui/chromeos/login/network_dropdown.h|cc changes

[sky, 2014-07-10 19:14:37]

LGTM

[sadrul, 2014-07-12 18:23:13]

+derat@ for third_party/cros_system_api owners (for DEPS addition in
ui/chromeos/DEPS)

[sadrul, 2014-07-12 18:30:40]

Committed patchset #3 manually as r282837 (presubmit successful).

[sadrul, 2014-07-13 04:03:52]

Committed patchset #5 manually as r282858 (presubmit successful).

[Daniel Erat, 2014-07-14 14:14:16]

lgtm for ui/chromeos/DEPS