Remove unused shutdown() function from WebSchedulerImpl.

Remove unused shutdown() function from WebSchedulerImpl.

Removes the unused shutdown() function from WebSchedulerImpl now that it is
no longer used by Blink.

BUG=467369
Committed: https://crrev.com/0d3caa98e164dca3ba17c0ff9330359ad8af3074
Cr-Commit-Position: refs/heads/master@{#321410}

[rmcilroy, 2015-03-18 12:51:15]

rmcilroy@chromium.org changed reviewers:
+ jamesr@chromium.org, skyostil@chromium.org

[rmcilroy, 2015-03-18 12:51:16]

jamesr: please take a look at mojo/

skyostil: please take a look at content/renderer/scheduler/

Thanks.

[Sami, 2015-03-18 15:48:13]

Yay, lgtm.

[jamesr, 2015-03-18 16:14:16]

mojo/ lgtm

[rmcilroy, 2015-03-18 16:20:15]

The CQ bit was checked by rmcilroy@chromium.org

[commit-bot: I haz the power, 2015-03-18 16:20:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1022443002/1

[commit-bot: I haz the power, 2015-03-18 16:23:23]

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

[commit-bot: I haz the power, 2015-03-18 16:23:24]

Try jobs failed on following builders:
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[rmcilroy, 2015-03-19 18:36:18]

The CQ bit was checked by rmcilroy@chromium.org

[rmcilroy, 2015-03-19 18:36:18]

The patchset sent to the CQ was uploaded after l-g-t-m from jamesr@chromium.org,
skyostil@chromium.org
Link to the patchset: https://codereview.chromium.org/1022443002/#ps20001
(title: "rebase")

[commit-bot: I haz the power, 2015-03-19 18:37:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1022443002/20001

[commit-bot: I haz the power, 2015-03-19 19:38:11]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-03-19 19:39:38]

Patchset 2 (id:??) landed as
https://crrev.com/0d3caa98e164dca3ba17c0ff9330359ad8af3074
Cr-Commit-Position: refs/heads/master@{#321410}