Shorten WebRTC signaling/worker thread names

Linux limits the thread name to 15 characters which was cutting off
the signaling/worker distinction.

Bug: None
Change-Id: Ibbbfdf1cedd0add91a8c3aa5c5b5cac6a06d4168
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1994050
Auto-Submit: Steve Anton <steveanton@chromium.org>
Reviewed-by: Harald Alvestrand <hta@chromium.org>
Commit-Queue: Harald Alvestrand <hta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#730115}

third_party/blink/renderer/modules/peerconnection/peer_connection_dependency_factory.cc

@@ -118,8 +118,8 @@ PeerConnectionDependencyFactory::PeerConnectionDependencyFactory(
           create_p2p_socket_dispatcher ? new P2PSocketDispatcher() : nullptr),
       signaling_thread_(nullptr),
       worker_thread_(nullptr),
-      chrome_signaling_thread_("Chrome_libJingle_Signaling"),
-      chrome_worker_thread_("Chrome_libJingle_WorkerThread") {
+      chrome_signaling_thread_("WebRTC_Signaling"),
+      chrome_worker_thread_("WebRTC_Worker") {
   TryScheduleStunProbeTrial();
 }