Merge the value of the push subscription id into the endpoint.

Merge the value of the push subscription id into the endpoint.

This change merges the subscription id belonging to a push subscription
into the endpoint, and deprecates the subscriptionId attribute.

The change is part of the following Intent to Deprecate thread:
https://groups.google.com/a/chromium.org/d/topic/blink-dev/CK13omVO5ds/discussion

When developers access the subscriptionId after all, they will get a
deprecation warning shown in their console:

> 'PushSubscription.subscriptionId' is deprecated and is now included in
> 'PushSubscription.endpoint'. It will be removed in Chrome 45, around
> August 2015.

This CL is part of a three-sided patch:
  [1] https://codereview.chromium.org/1099673002/
  [2] This CL.
  [3] https://codereview.chromium.org/1078873004/

BUG=477401
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=194922

[Peter Beverloo, 2015-04-20 18:10:27]

peter@chromium.org changed reviewers:
+ mvanouwerkerk@chromium.org

[Peter Beverloo, 2015-04-20 18:10:28]

+mvanouwerkerk

[Peter Beverloo, 2015-04-20 18:11:18]

peter@chromium.org changed reviewers:
+ mkwst@chromium.org

[Peter Beverloo, 2015-04-20 18:11:18]

Also +mkwst for the deprecation addition. This is blocked on the Intent to
Deprecate. (Which will hopefully be resolved tomorrow.)

[Mike West, 2015-04-20 18:20:59]

LGTM, but please wait for that thread to resolve.

[Michael van Ouwerkerk, 2015-04-21 11:03:00]

lgtm

[Peter Beverloo, 2015-05-05 12:11:13]

The CQ bit was checked by peter@chromium.org

[Peter Beverloo, 2015-05-05 12:11:13]

The patchset sent to the CQ was uploaded after l-g-t-m from mkwst@chromium.org,
mvanouwerkerk@chromium.org
Link to the patchset: https://codereview.chromium.org/1084683003/#ps40001
(title: "rebase")

[commit-bot: I haz the power, 2015-05-05 12:11:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1084683003/40001

[commit-bot: I haz the power, 2015-05-05 12:13:45]

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

[commit-bot: I haz the power, 2015-05-05 12:13:46]

Try jobs failed on following builders:
  mac_blink_compile_dbg on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/mac_blink_compile_dbg/bu...)

[Peter Beverloo, 2015-05-05 12:19:19]

The CQ bit was checked by peter@chromium.org

[Peter Beverloo, 2015-05-05 12:19:20]

The patchset sent to the CQ was uploaded after l-g-t-m from mkwst@chromium.org,
mvanouwerkerk@chromium.org
Link to the patchset: https://codereview.chromium.org/1084683003/#ps60001
(title: "rebase")

[commit-bot: I haz the power, 2015-05-05 12:19:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1084683003/60001

[commit-bot: I haz the power, 2015-05-05 13:40:20]

Committed patchset #4 (id:60001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=194922