Clean up the deprecation warning for Request.context

Clean up the deprecation warning for Request.context

Request.context is already removed in M46 and thus the deprecation message
string is no longer needed.

BUG=515786
Committed: https://crrev.com/53588a7c8556f13b3c8156e5b9e12339408035bc
Cr-Commit-Position: refs/heads/master@{#361254}

[hiroshige, 2015-09-29 05:58:03]

The CQ bit was checked by hiroshige@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-29 05:58:28]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373713004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373713004/1

[commit-bot: I haz the power, 2015-09-29 06:24:21]

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

[commit-bot: I haz the power, 2015-09-29 06:24:22]

Dry run: Try jobs failed on following builders:
  android_clang_dbg_recipe on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_clang_d...)

[hiroshige, 2015-10-28 11:53:24]

The CQ bit was checked by hiroshige@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-10-28 11:53:53]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373713004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373713004/1

[commit-bot: I haz the power, 2015-10-28 12:56:46]

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

[commit-bot: I haz the power, 2015-10-28 12:56:46]

Dry run: Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[hiroshige, 2015-11-09 18:06:18]

The CQ bit was checked by hiroshige@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-11-09 18:07:14]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373713004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373713004/1

[commit-bot: I haz the power, 2015-11-09 20:37:06]

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

[commit-bot: I haz the power, 2015-11-09 20:37:07]

Dry run: This issue passed the CQ dry run.

[hiroshige, 2015-11-23 19:00:24]

The CQ bit was checked by hiroshige@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-11-23 19:04:10]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373713004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373713004/1

[hiroshige, 2015-11-23 19:41:02]

hiroshige@chromium.org changed reviewers:
+ kinuko@chromium.org

[hiroshige, 2015-11-23 19:41:02]

PTAL as a core/ owner.

This is partial revert of
https://codereview.chromium.org/1287273002/.

[commit-bot: I haz the power, 2015-11-23 20:39:03]

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

[commit-bot: I haz the power, 2015-11-23 20:39:04]

Dry run: This issue passed the CQ dry run.

[kinuko, 2015-11-24 01:36:58]

lgtm

[hiroshige, 2015-11-24 04:33:22]

The CQ bit was checked by hiroshige@chromium.org

[commit-bot: I haz the power, 2015-11-24 04:36:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373713004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373713004/1

[commit-bot: I haz the power, 2015-11-24 04:42:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-24 04:42:52]

Patchset 1 (id:??) landed as
https://crrev.com/53588a7c8556f13b3c8156e5b9e12339408035bc
Cr-Commit-Position: refs/heads/master@{#361254}