[Telemetry] Combine SysfsPlatformBackend into LinuxBasedPlatformBackend.

[Telemetry] Combine SysfsPlatformBackend into LinuxBasedPlatformBackend.

Sysfs related functionality should have never been a separate Platform. There
should just be one Platform at a time.

BUG=

Committed: https://crrev.com/fcf8643d31301eea990a4c42d7d8c9fc30cc33ec
Cr-Commit-Position: refs/heads/master@{#292269}

[tonyg, 2014-08-27 15:33:56]

tonyg@chromium.org changed reviewers:
+ dtu@chromium.org

[dtu, 2014-08-27 22:32:57]

The CQ bit was checked by dtu@chromium.org

[dtu, 2014-08-27 22:32:58]

lgtm

[commit-bot: I haz the power, 2014-08-27 22:34:27]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tonyg@chromium.org/509043002/1

[commit-bot: I haz the power, 2014-08-27 23:16:24]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_arm64_dbg_recipe on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_arm64_d...)

[commit-bot: I haz the power, 2014-08-27 23:44:24]

Committed patchset #1 (id:1) as e05500aaea3c40e7ef95bd33f34170467d88dffd

[commit-bot: I haz the power, 2014-09-10 02:55:41]

Patchset 1 (id:??) landed as
https://crrev.com/fcf8643d31301eea990a4c42d7d8c9fc30cc33ec
Cr-Commit-Position: refs/heads/master@{#292269}