Thread::Stop() must be called before any subclass's destructor completes.

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 # running overnight and removing outdated bugs/suppressions.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 575 matching lines @@
 }
 {
   bug_100020
   ThreadSanitizer:Race
   fun:linked_ptr_internal::join
   fun:linked_ptr::copy
   ...
   fun:HostContentSettingsMap::GetDefaultContentSetting
 }
 {
-  bug_102134a
-  ThreadSanitizer:Race
-  fun:content::BrowserThreadImpl::~BrowserThreadImpl
-  fun:content::TestBrowserThread::~TestBrowserThread
-}
-{
-  bug_102134b
-  ThreadSanitizer:Race
-  fun:content::BrowserThread::~BrowserThread
-  fun:content::DeprecatedBrowserThread::~DeprecatedBrowserThread
-}
-{
   bug_102327_a
   ThreadSanitizer:Race
   fun:tracked_objects::ThreadData::Initialize
   fun:tracked_objects::ThreadData::InitializeThreadContext
   fun:base::Thread::ThreadMain
   fun:base::::ThreadFunc
 }
 {
   bug_102327_b
   ThreadSanitizer:Race
   ...
   fun:tracked_objects::ThreadData::TallyABirthIfActive
   fun:base::PosixDynamicThreadPool::PendingTask::PendingTask
   fun:base::PosixDynamicThreadPool::WaitForTask
   fun:base::::WorkerThread::ThreadMain
   fun:base::::ThreadFunc
 }