Fix race condition in DataFetcherSharedMemoryBase

tools/valgrind/tsan/suppressions.txt

Index: tools/valgrind/tsan/suppressions.txt
diff --git a/tools/valgrind/tsan/suppressions.txt b/tools/valgrind/tsan/suppressions.txt
index b969b845cd2474340fce553aea723a5262a1a7b7..5251a61db4a7f1bda9f333b4d90c785aef19e623 100644
--- a/tools/valgrind/tsan/suppressions.txt
+++ b/tools/valgrind/tsan/suppressions.txt
@@ -1129,17 +1129,3 @@
   fun:content::UtilityThreadImpl::UtilityThreadImpl
   fun:content::UtilityMainThread::InitInternal
 }
-{
-   bug_284959
-   ThreadSanitizer:Race
-   fun:std::_Rb_tree_insert_and_rebalance
-   fun:std::_Rb_tree::_M_insert_
-   fun:std::_Rb_tree::_M_insert_unique_
-   fun:std::map::insert
-   fun:std::map::operator[]
-   fun:content::DataFetcherSharedMemoryBase::GetSharedMemory
-   fun:content::DataFetcherSharedMemoryBase::GetSharedMemoryBuffer
-   fun:content::DataFetcherSharedMemoryBase::StartFetchingDeviceData
-   fun:content::::DataFetcherSharedMemoryBaseTest_DoesPollMotionAndOrientation_Test::TestBody
-   fun:testing::internal::HandleSehExceptionsInMethodIfSupported
-}