Valgrind: Suppress a new variation of a libpng error and widen the mac LoadLibrary suppression.

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 # running overnight and removing outdated bugs/suppressions.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 312 matching lines @@
    # Plugins are deliberately not unloaded (on shutdown) on the Mac, in order to
    # prevent crashes for those that don't unload cleanly.
    plugin_unload
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN4base17LoadNativeLibraryERK8FilePathPSs
    fun:_ZN6webkit5npapi9PluginLib4LoadEv
    fun:_ZN6webkit5npapi9PluginLib13NP_InitializeEv
    fun:_ZN6webkit5npapi21WebPluginDelegateImpl6CreateERK8FilePathRKSsy
    fun:_ZN19TestWebViewDelegate20CreatePluginDelegateERK8FilePathRKSs
-   fun:_ZN6webkit5npapi13WebPluginImpl10initializeEPN6WebKit18WebPluginContainerE
 }
 {
    # Mac Sandbox test cases are registered in a global map.  This code is only
    # used in the unit test binary.
    Mac_Sandbox_Intentional_Leak1
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN11sandboxtest8internal19RegisterSandboxTestIN12_GLOBAL__N_*
    ...
    fun:_ZN16ImageLoaderMachO18doModInitFunctionsERKN11ImageLoader11LinkContextE
@@ skipping 1649 matching lines @@
 }
 {
    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
 }