Revert of Migrate DeviceUtils.ReadFile to adb_wrapper

Revert of Migrate DeviceUtils.ReadFile to adb_wrapper (patchset #6 id:100001 of https://codereview.chromium.org/775333002/)

Reason for revert:
Broke telemetry android_browser_backend due to missing client change

Original issue's description:
> Migrate DeviceUtils.ReadFile to adb_wrapper
>
> The implementation is based on a simple 'cat' run by shell on the
> device (with optional as_root).
>
> Interface changes:
> - The return value is a string (instead of a list of lines).
> - An exception is raised if the file cannot be read (instead of returning an empty list).
>
> BUG=267773
>
> Committed: https://crrev.com/c75a264a0386df5931a9b6ac8c81337794d034d0
> Cr-Commit-Position: refs/heads/master@{#307672}

TBR=jbudorick@chromium.org,skyostil@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=267773
Committed: https://crrev.com/dc3b7db40fa6f66cd5757b2e807493a91379dc7f
Cr-Commit-Position: refs/heads/master@{#307711}

[perezju, 2014-12-10 16:07:54]

Created Revert of Migrate DeviceUtils.ReadFile to adb_wrapper

[commit-bot: I haz the power, 2014-12-10 16:08:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/796433002/1

[commit-bot: I haz the power, 2014-12-10 16:09:00]

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

[commit-bot: I haz the power, 2014-12-10 16:09:01]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[jbudorick, 2014-12-10 16:10:03]

lgtm :(

[perezju, 2014-12-10 16:11:31]

The CQ bit was checked by perezju@chromium.org

[perezju, 2014-12-10 16:11:38]

The CQ bit was unchecked by perezju@chromium.org

[Sami, 2014-12-10 16:11:45]

On 2014/12/10 16:10:03, jbudorick wrote:
> lgtm :(

lgtm x2

[perezju, 2014-12-10 16:12:04]

The CQ bit was checked by perezju@chromium.org

[commit-bot: I haz the power, 2014-12-10 16:12:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/796433002/1

[commit-bot: I haz the power, 2014-12-10 16:14:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-10 16:15:38]

Patchset 1 (id:??) landed as
https://crrev.com/dc3b7db40fa6f66cd5757b2e807493a91379dc7f
Cr-Commit-Position: refs/heads/master@{#307711}