deprecate non-phantom weak callbacks

Reland: deprecate non-phantom weak callbacks

BUG=

Committed: https://crrev.com/3be656fb55ad49834ec8ec0a57ba858bb1b21f37
Cr-Commit-Position: refs/heads/master@{#28094}

[jochen (gone - plz use gerrit), 2015-04-27 12:30:53]

jochen@chromium.org changed reviewers:
+ jochen@chromium.org

[jochen (gone - plz use gerrit), 2015-04-27 12:30:53]

lgtm

[dcarney, 2015-04-27 12:31:13]

The CQ bit was checked by dcarney@chromium.org

[commit-bot: I haz the power, 2015-04-27 12:31:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1103173002/1

[commit-bot: I haz the power, 2015-04-27 13:06:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-27 13:07:00]

Patchset 1 (id:??) landed as
https://crrev.com/39c31da2142ab0fca9dae279b9e59cd4951a1982
Cr-Commit-Position: refs/heads/master@{#28077}

[Michael Achenbach, 2015-04-27 13:30:26]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1104163002/ by machenbach@chromium.org.

The reason for reverting is: [Sheriff] Fails compilation on chromium android:
http://build.chromium.org/p/client.v8/builders/Android%20Builder/builds/4131

Is the chromium version our builder used maybe too old (it uses lkcr)? In that
case please reland as soon as it's up-to-date..

[dcarney, 2015-04-28 08:31:34]

The CQ bit was checked by dcarney@chromium.org

[commit-bot: I haz the power, 2015-04-28 08:31:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1103173002/1

[commit-bot: I haz the power, 2015-04-28 08:31:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-28 08:32:08]

Patchset 1 (id:??) landed as
https://crrev.com/3be656fb55ad49834ec8ec0a57ba858bb1b21f37
Cr-Commit-Position: refs/heads/master@{#28094}

[Michael Achenbach, 2015-04-29 05:56:37]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1117623002/ by machenbach@chromium.org.

The reason for reverting is: [Sheriff] This is still used and now blocks the
roll here:
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp....