Provision devices: use ReadFile/WriteFile to load/restore adb keys

Provision devices: use ReadFile/WriteFile to load/restore adb keys

Instead of using a cat/echo combination to read and write adb keys one
by one, we can now use the dedicated and more robust ReadFile/WriteFile.

Depends on: https://codereview.chromium.org/806843002/

BUG=436133
Committed: https://crrev.com/eda10ed8796186f0781b81cbb8a1951ab013b7a6
Cr-Commit-Position: refs/heads/master@{#313274}

[perezju, 2014-12-15 15:33:21]

perezju@chromium.org changed reviewers:
+ jbudorick@chromium.org

[perezju, 2014-12-15 15:33:21]

(hopefully) straightforward, but depends on landing the interface change for
DeviceUtils.ReadFile

[jbudorick, 2014-12-15 23:13:43]

lgtm

https://codereview.chromium.org/801283004/diff/1/build/android/provision_devi...
File build/android/provision_devices.py (right):

https://codereview.chromium.org/801283004/diff/1/build/android/provision_devi...
build/android/provision_devices.py:122: adb_keys =
device.ReadFile(constants.ADB_KEYS_FILE, as_root=True)
These will both now check a return value where they weren't before. I think
that's ok -- we want to fail loudly if we fail either of these -- but, as with
the ReadFile CL, you might hit some turbulence.

[perezju, 2015-01-27 10:42:20]

The CQ bit was checked by perezju@chromium.org

[commit-bot: I haz the power, 2015-01-27 10:43:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/801283004/1

[commit-bot: I haz the power, 2015-01-27 11:58:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-27 11:58:50]

Try jobs failed on following builders:
  win_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu_triggered...)

[perezju, 2015-01-27 12:07:52]

The CQ bit was checked by perezju@chromium.org

[commit-bot: I haz the power, 2015-01-27 12:08:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/801283004/1

[commit-bot: I haz the power, 2015-01-27 12:08:29]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-27 12:08:30]

Try jobs failed on following builders:
  win_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu/builds/11...)
  win_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu_triggered...)

[perezju, 2015-01-27 14:31:01]

The CQ bit was checked by perezju@chromium.org

[commit-bot: I haz the power, 2015-01-27 14:32:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/801283004/1

[commit-bot: I haz the power, 2015-01-27 14:33:26]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-27 14:34:32]

Patchset 1 (id:??) landed as
https://crrev.com/eda10ed8796186f0781b81cbb8a1951ab013b7a6
Cr-Commit-Position: refs/heads/master@{#313274}