Handle push resubscribes with no sender info (avoids DCHECK)

Handle push resubscribes with no sender info (avoids DCHECK)

- Prior to this patch you would fail a DCHECK if you called
  PushManager.subscribe() with a sender id or key and then
  PushManager.subscribe() without a sender id or key.

- This fixes that and only allows resubscribing with no sender info
when the original subscribe was made with a gcm_sender_id.
Otherwise we throw an AbortError - no key provided.

BUG=659230
Review-Url: https://codereview.chromium.org/2469293002
Cr-Commit-Position: refs/heads/master@{#430601}
(cherry picked from commit d8e7aa32e6e15b1ce0cde3a6ccf878fb16ffc816)

Committed: https://chromium.googlesource.com/chromium/src/+/bd071b0aaa4d50bb0cd48becbd108fa87802c728

[harkness, 2016-11-09 15:41:28]

Description was changed from

==========
Handle push resubscribes with no sender info (avoids DCHECK)

- Prior to this patch you would fail a DCHECK if you called
  PushManager.subscribe() with a sender id or key and then
  PushManager.subscribe() without a sender id or key.

- This fixes that and only allows resubscribing with no sender info
when the original subscribe was made with a gcm_sender_id.
Otherwise we throw an AbortError - no key provided.

BUG=659230

Review-Url: https://codereview.chromium.org/2469293002
Cr-Commit-Position: refs/heads/master@{#430601}
(cherry picked from commit d8e7aa32e6e15b1ce0cde3a6ccf878fb16ffc816)
==========

to

==========
Handle push resubscribes with no sender info (avoids DCHECK)

- Prior to this patch you would fail a DCHECK if you called
  PushManager.subscribe() with a sender id or key and then
  PushManager.subscribe() without a sender id or key.

- This fixes that and only allows resubscribing with no sender info
when the original subscribe was made with a gcm_sender_id.
Otherwise we throw an AbortError - no key provided.

BUG=659230

Review-Url: https://codereview.chromium.org/2469293002
Cr-Commit-Position: refs/heads/master@{#430601}
(cherry picked from commit d8e7aa32e6e15b1ce0cde3a6ccf878fb16ffc816)

Committed:
https://chromium.googlesource.com/chromium/src/+/bd071b0aaa4d50bb0cd48becbd10...
==========

[harkness, 2016-11-09 15:41:30]

Committed patchset #2 (id:20001) manually as
bd071b0aaa4d50bb0cd48becbd108fa87802c728.

[jennyz, 2016-11-18 00:09:13]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/2511133003/ by jennyz@chromium.org.

The reason for reverting is:
https://uberchromegw.corp.google.com/i/chromeos.chrome/builders/Linux%20Chrom....