Fix the Chromium crash when creating an answer without a remote description.

Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method GetOptionsForAnswer
won't crash when there is no remote description. WebRtcSessionDescriptionFactory 
will handle the null remote description.

TBR=deadbeef@webrtc.org
BUG=chromium:757830
Review-Url: https://codereview.webrtc.org/3006723002
Cr-Commit-Position: refs/heads/master@{#19589}
Committed: https://chromium.googlesource.com/external/webrtc/+/141aacbf0b2df237e3e509ead278b770a2a04ad7

[Zhi Huang, 2017-08-28 18:42:52]

The CQ bit was checked by zhihuang@webrtc.org to run a CQ dry run

[commit-bot: I haz the power, 2017-08-28 18:42:59]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-08-28 19:09:09]

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

[commit-bot: I haz the power, 2017-08-28 19:09:10]

Dry run: This issue passed the CQ dry run.

[Zhi Huang, 2017-08-28 20:32:44]

Description was changed from

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash in the release build when there is no remote description.
WebRtcSessionDescriptionFactory will handle the null remote description.

BUG=chromium:757830
==========

to

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash when there is no remote description.
WebRtcSessionDescriptionFactory will handle the null remote description.

BUG=chromium:757830
==========

[Zhi Huang, 2017-08-28 20:33:14]

Description was changed from

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash when there is no remote description.
WebRtcSessionDescriptionFactory will handle the null remote description.

BUG=chromium:757830
==========

to

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash when there is no remote description. WebRtcSessionDescriptionFactory

will handle the null remote description.

BUG=chromium:757830
==========

[Zhi Huang, 2017-08-28 20:36:35]

zhihuang@webrtc.org changed reviewers:
+ deadbeef@webrtc.org

[Zhi Huang, 2017-08-28 20:36:35]

Hi Taylor,

This is an one-line change to fix the chromium crash. PTAL.

[Taylor Brandstetter, 2017-08-29 02:11:09]

lgtm. Though can you add a test for "CreateAnswer fails if no offer has been
set" in peerconnectioninterface_unittest.cc?

[Zhi Huang, 2017-08-29 19:47:33]

Patchset #2 (id:20001) has been deleted

[Zhi Huang, 2017-08-29 19:48:08]

The CQ bit was checked by zhihuang@webrtc.org to run a CQ dry run

[commit-bot: I haz the power, 2017-08-29 19:48:17]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-08-29 20:20:21]

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

[commit-bot: I haz the power, 2017-08-29 20:20:22]

Dry run: This issue passed the CQ dry run.

[Zhi Huang, 2017-08-29 20:21:37]

Description was changed from

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash when there is no remote description. WebRtcSessionDescriptionFactory

will handle the null remote description.

BUG=chromium:757830
==========

to

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash when there is no remote description. WebRtcSessionDescriptionFactory

will handle the null remote description.

TBR=deadbeef@webrtc.org
BUG=chromium:757830
==========

[Zhi Huang, 2017-08-29 20:21:46]

The CQ bit was checked by zhihuang@webrtc.org

[Zhi Huang, 2017-08-29 20:21:47]

The patchset sent to the CQ was uploaded after l-g-t-m from deadbeef@webrtc.org
Link to the patchset: https://codereview.webrtc.org/3006723002/#ps40001 (title:
"Add a unit test.")

[commit-bot: I haz the power, 2017-08-29 20:21:52]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-08-29 20:23:54]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1504038106783380,
"parent_rev": "1dca9d513ada149c444a7316e16e91d53635ab5b", "commit_rev":
"141aacbf0b2df237e3e509ead278b770a2a04ad7"}

[commit-bot: I haz the power, 2017-08-29 20:23:58]

Description was changed from

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash when there is no remote description. WebRtcSessionDescriptionFactory

will handle the null remote description.

TBR=deadbeef@webrtc.org
BUG=chromium:757830
==========

to

==========
Fix the Chromium crash when creating an answer without a remote description.

Replacing the RTC_DCHECK with an if condition so that the method
GetOptionsForAnswer
won't crash when there is no remote description. WebRtcSessionDescriptionFactory

will handle the null remote description.

TBR=deadbeef@webrtc.org
BUG=chromium:757830

Review-Url: https://codereview.webrtc.org/3006723002
Cr-Commit-Position: refs/heads/master@{#19589}
Committed:
https://chromium.googlesource.com/external/webrtc/+/141aacbf0b2df237e3e509ead...
==========

[commit-bot: I haz the power, 2017-08-29 20:24:01]

Committed patchset #2 (id:40001) as
https://chromium.googlesource.com/external/webrtc/+/141aacbf0b2df237e3e509ead...