Mac: Suppress mysterious valgrind error from after a bot restart....

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 # running overnight and removing outdated bugs/suppressions.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 1006 matching lines @@
    fun:_ZN19extension_file_util13LoadExtensionERK8FilePathbPSs
    fun:_ZN12CrxInstaller15CompleteInstallEv
    fun:_Z16DispatchToMethodI12CrxInstallerMS0_FvvEEvPT_T0_RK6Tuple0
    fun:_ZN14RunnableMethodI12CrxInstallerMS0_FvvE6Tuple0E3RunEv
    fun:_ZN11MessageLoop7RunTaskEP4Task
    fun:_ZN11MessageLoop21DeferOrRunPendingTaskERKNS_11PendingTaskE
    fun:_ZN11MessageLoop6DoWorkEv
    fun:_ZN4base19MessagePumpLibevent3RunEPNS_11MessagePump8DelegateE
    fun:_ZN11MessageLoop11RunInternalEv
 }
+# Maybe this needs to be moved up to section 1?
+{
+   bug_42593
+   Memcheck:Leak
+   fun:calloc
+   fun:_internal_class_createInstanceFromZone
+   fun:_internal_class_createInstance
+   fun:+[NSObject allocWithZone:]
+   fun:_decodeObjectBinary
+   fun:_decodeObject
+   fun:-[NSButtonCell initWithCoder:]
+   fun:_decodeObjectBinary
+   fun:_decodeObject
+   fun:-[NSControl initWithCoder:]
+   fun:-[NSButton initWithCoder:]
+   fun:_decodeObjectBinary
+   fun:_decodeObject
+   fun:-[NSNibConnector initWithCoder:]
+   fun:-[NSNibOutletConnector initWithCoder:]
+   fun:_decodeObjectBinary
+   fun:-[NSKeyedUnarchiver _decodeArrayOfObjectsForKey:]
+   fun:-[NSArray(NSArray) initWithCoder:]
+   fun:_decodeObjectBinary
+   fun:_decodeObject
+   fun:-[NSIBObjectData initWithCoder:]
+   fun:_decodeObjectBinary
+}