Remove unused suppression.

This was fixed in https://codereview.chromium.org/26784003 which removed the
problematic InformDelegateDownloadDataIfNecessary method.

BUG=296883

Review URL: https://codereview.chromium.org/1169453006

Cr-Original-Commit-Position: refs/heads/master@{#332935}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 2cad80e32ba9f877bb2d304e4ba9e0a4444ef722

sanitizers/tsan_suppressions.cc

@@ -141,9 +141,6 @@ char kTSanDefaultSuppressions[] =
 // http://crbug.com/285242
 "race:media::PulseAudioOutputStream::SetVolume\n"
 
-// http://crbug.com/296883
-"race:net::URLFetcherCore::Stop\n"
-
 // http://crbug.com/308590
 "race:CustomThreadWatcher::~CustomThreadWatcher\n"