When updating md5sum_bin, wipe the directory first

When updating md5sum_bin, wipe the directory first

Fixes the case where the command would fail if the files on device were
owned by root, but adbd is currently running non-root.

BUG=

Committed: https://crrev.com/90089446b07a468f851a17ed8e2e62355eee9c21
Cr-Commit-Position: refs/heads/master@{#346661}

[agrieve, 2015-09-01 03:23:05]

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

[agrieve, 2015-09-01 03:23:05]

This was the case on one of my devices. 

Confirmed that a manual run of "adb push" reported that it worked, but an "ls
-l" of the md5sum directory showed the files were not changed.

[jbudorick, 2015-09-01 03:36:25]

lgtm w/ nit

https://codereview.chromium.org/1303363005/diff/1/build/android/pylib/utils/m...
File build/android/pylib/utils/md5sum.py (right):

https://codereview.chromium.org/1303363005/diff/1/build/android/pylib/utils/m...
build/android/pylib/utils/md5sum.py:101: device.RunShellCommand(['rm', '-rf',
MD5SUM_DEVICE_LIB_PATH],
Hm, we have a mechanism for rooted push in DeviceUtils.WriteFile, but that's
more for writing text files.

https://codereview.chromium.org/1303363005/diff/1/build/android/pylib/utils/m...
build/android/pylib/utils/md5sum.py:102: as_root=True)
nit: check_return=True

[agrieve, 2015-09-01 13:58:21]

https://codereview.chromium.org/1303363005/diff/1/build/android/pylib/utils/m...
File build/android/pylib/utils/md5sum.py (right):

https://codereview.chromium.org/1303363005/diff/1/build/android/pylib/utils/m...
build/android/pylib/utils/md5sum.py:101: device.RunShellCommand(['rm', '-rf',
MD5SUM_DEVICE_LIB_PATH],
On 2015/09/01 03:36:25, jbudorick wrote:
> Hm, we have a mechanism for rooted push in DeviceUtils.WriteFile, but that's
> more for writing text files.

Acknowledged.

https://codereview.chromium.org/1303363005/diff/1/build/android/pylib/utils/m...
build/android/pylib/utils/md5sum.py:102: as_root=True)
On 2015/09/01 03:36:25, jbudorick wrote:
> nit: check_return=True

Done.

[agrieve, 2015-09-01 13:58:26]

The CQ bit was checked by agrieve@chromium.org

[agrieve, 2015-09-01 13:58:27]

The patchset sent to the CQ was uploaded after l-g-t-m from
jbudorick@chromium.org
Link to the patchset: https://codereview.chromium.org/1303363005/#ps20001
(title: "check_return=Tue")

[commit-bot: I haz the power, 2015-09-01 13:58:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1303363005/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1303363005/20001

[commit-bot: I haz the power, 2015-09-01 14:31:14]

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

[commit-bot: I haz the power, 2015-09-01 14:31:14]

Try jobs failed on following builders:
  linux_chromium_asan_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[agrieve, 2015-09-01 14:53:50]

The CQ bit was checked by agrieve@chromium.org

[commit-bot: I haz the power, 2015-09-01 14:53:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1303363005/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1303363005/20001

[commit-bot: I haz the power, 2015-09-01 15:36:46]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-01 15:37:24]

Patchset 2 (id:??) landed as
https://crrev.com/90089446b07a468f851a17ed8e2e62355eee9c21
Cr-Commit-Position: refs/heads/master@{#346661}