google_apis: Migrate callers of message_loop_proxy() to task_runner()

google_apis: Migrate callers of message_loop_proxy() to task_runner()

Migrate callers of {MessageLoop,Thread}::message_loop_proxy() to
{MessageLoop,Thread}::task_runner(). Since the types at the call sites
have already been updated, this is just a bulk rename.

BUG=465354
Committed: https://crrev.com/8c36b0c96bee3fea8e5b125bacae03d3c537a386
Cr-Commit-Position: refs/heads/master@{#334768}

[Sami, 2015-06-12 17:25:42]

skyostil@chromium.org changed reviewers:
+ rogerta@chromium.org

[Roger Tawa OOO till Jul 10th, 2015-06-12 18:32:11]

lgtm

[Sami, 2015-06-16 22:57:55]

The CQ bit was checked by skyostil@chromium.org

[commit-bot: I haz the power, 2015-06-16 22:59:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1184713004/1

[commit-bot: I haz the power, 2015-06-16 23:06:22]

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

[commit-bot: I haz the power, 2015-06-16 23:06:23]

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...)
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[Sami, 2015-06-17 00:56:10]

The CQ bit was checked by skyostil@chromium.org

[Sami, 2015-06-17 00:56:10]

The patchset sent to the CQ was uploaded after l-g-t-m from rogerta@chromium.org
Link to the patchset: https://codereview.chromium.org/1184713004/#ps20001
(title: "Rebased.")

[commit-bot: I haz the power, 2015-06-17 00:57:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1184713004/20001

[commit-bot: I haz the power, 2015-06-17 01:59:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-17 02:00:04]

Patchset 2 (id:??) landed as
https://crrev.com/8c36b0c96bee3fea8e5b125bacae03d3c537a386
Cr-Commit-Position: refs/heads/master@{#334768}