Android: fix battery status API charging state.

Android: fix battery status API charging state.

Define charging attribute in terms of whether the device is
plugged in or not. Previously it was defined in terms of
BATTERY_STATUS_DISCHARGING property but some phones report
BATTERY_STATUS_NOT_CHARGING when the battery is not charging.
Also modified the tests accordingly.

TEST=http://jsbin.com/battery-status-test
BUG=360068
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=288361

[Miguel Garcia, 2014-08-08 11:43:14]

lgtm

[Michael van Ouwerkerk, 2014-08-08 12:17:24]

lgtm

[timvolodine, 2014-08-08 13:09:37]

The CQ bit was checked by timvolodine@chromium.org

[commit-bot: I haz the power, 2014-08-08 13:10:52]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/timvolodine@chromium.org/451773002/20001

[commit-bot: I haz the power, 2014-08-08 14:35:51]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_triggered...)
  win_chromium_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel/...)

[commit-bot: I haz the power, 2014-08-08 15:00:39]

Change committed as 288361