Remove suppression of race:browser_sync::PasswordChangeProcessor::Disconnect.

tools/valgrind/tsan/suppressions.txt

 # There are a few kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 1106 matching lines @@
   fun:testing::internal::FunctionMocker::Invoke
   fun:content::::MockWebRtcAudioCapturerSink::CaptureData
   fun:content::::MockWebRtcAudioCapturerSink::CaptureData
   fun:content::WebRtcAudioCapturerSinkOwner::CaptureData
   fun:content::WebRtcLocalAudioTrack::Capture
   fun:content::WebRtcAudioCapturer::TrackOwner::Capture
   fun:content::WebRtcAudioCapturer::Capture
   fun:content::::FakeAudioThread::ThreadMain
   fun:base::::ThreadFunc
 }
-{
-  bug_297194
-  ThreadSanitizer:Race
-  fun:scoped_refptr::operator=
-  fun:browser_sync::PasswordChangeProcessor::Disconnect
-  fun:browser_sync::PasswordDataTypeController::DisconnectProcessor
-  fun:browser_sync::NonFrontendDataTypeController::BackendComponentsContainer::Disconnect
-  fun:browser_sync::NonFrontendDataTypeController::Stop
-  fun:browser_sync::ModelAssociationManager::Stop
-  fun:browser_sync::DataTypeManagerImpl::StopImpl
-  fun:browser_sync::DataTypeManagerImpl::Stop
-  fun:ProfileSyncService::ShutdownImpl
-  fun:ProfileSyncService::Shutdown
-}