Valgrind: Add a new mac suppression and update an existing one.

tools/valgrind/memcheck/suppressions_mac.txt

 # There are three kinds of suppressions in this file:
 # 1. Third party stuff we have no control over.
 #
 # 2. Intentional unit test errors, 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.
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 1973 matching lines @@
    fun:malloc_set_zone_name
    fun:init__zone0
    fun:setenv$UNIX2003
    fun:_ZN12_GLOBAL__N_115EnvironmentImpl10SetVarImplEPKcRKSs
    fun:_ZN12_GLOBAL__N_115EnvironmentImpl6SetVarEPKcRKSs
    fun:_Z18AppendToPythonPathRK8FilePath
    fun:_ZN3net10TestServer13SetPythonPathEv
    fun:_ZN3net10TestServer5StartEv
    fun:_ZN12_GLOBAL__N_132MimeTypeTests_MimeTypeTests_Test8TestBodyEv
 }
+{
+   bug_105323
+   Memcheck:Leak
+   fun:_Znw*
+   fun:_ZN15tracked_objects10ThreadData3GetEv
+   fun:_ZN15tracked_objects10ThreadData32TallyRunOnWorkerThreadIfTrackingEPKNS_6BirthsERKNS_11TrackedTimeES6_S6_
+   fun:_ZN4base12_GLOBAL__N_112WorkerThread10ThreadMainEv
+   fun:_ZN4base12_GLOBAL__N_110ThreadFuncEPv
+}