Revert "Disable flaky */ConnectionTest.VideoWithSlowSignaling/*"

This reverts commit 108797c3.

Reason for revert: Underlaying problem fixed in webrtc. https://webrtc-review.googlesource.com/c/src/+/193063

Original change's description:
> Disable flaky */ConnectionTest.VideoWithSlowSignaling/*
>
> Bug: 1143311
> Change-Id: I131bb5b58f8f403d2752288c6e2c4a8ec11e15a7
> NoTry: True
> Tbr: joedow@chromium.org
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2523302
> Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
> Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#825119}

TBR=xiaochengh@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1143311
Change-Id: I0aa89b44e48335b08b0615c6ba9edc6c405218fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2544122Reviewed-by: Per Kjellander <perkj@chromium.org>
Commit-Queue: Per Kjellander <perkj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828132}

remoting/protocol/connection_unittest.cc

@@ -543,10 +543,9 @@ TEST_P(ConnectionTest, Video) {
   }
 }
 
-// TODO(crbug.com/1143311): Test is flaky.
 // Verifies that the VideoStream doesn't loose any video frames while the
 // connection is being established.
-TEST_P(ConnectionTest, DISABLED_VideoWithSlowSignaling) {
+TEST_P(ConnectionTest, VideoWithSlowSignaling) {
   // Add signaling delay to slow down connection handshake.
   host_session_->set_signaling_delay(base::TimeDelta::FromMilliseconds(100));
   client_session_->set_signaling_delay(base::TimeDelta::FromMilliseconds(100));