Revert of Delete class SSRCDatabase, and its global ssrc registry. (patchset #20 id:370001 of https://codereview.webrtc.org/2644303002/ )
Reason for revert:
Breaks webrtc_perf_tests reliably:
https://build.chromium.org/p/client.webrtc.perf/builders/Android32%20Tests%20%28L%20Nexus5%29/builds/1780
https://build.chromium.org/p/client.webrtc.perf/builders/Android32%20Tests%20%28L%20Nexus4%29/builds/178
We're actively working on getting a quick version of webrtc_perf_tests up on the trybots again to prevent breakages like this: https://bugs.chromium.org/p/webrtc/issues/detail?id=7101
Original issue's description:
> Delete class SSRCDatabase, and its global ssrc registry,
> and the method RTPSender::GenerateNewSSRC.
>
> It's now mandatory for higher layers to call SetSSRC, RTPSender
> no longer allocates any ssrc by default.
>
> BUG=webrtc:4306,webrtc:6887
>
> Review-Url: https://codereview.webrtc.org/2644303002
> Cr-Commit-Position: refs/heads/master@{#16670}
> Committed: b78d4d1383
TBR=solenberg@webrtc.org,stefan@webrtc.org,danilchap@webrtc.org,ivoc@webrtc.org,nisse@webrtc.org
NOTRY=True
BUG=webrtc:4306,webrtc:6887
Review-Url: https://codereview.webrtc.org/2700413002
Cr-Commit-Position: refs/heads/master@{#16693}
b5848ecbf5