Update from https://crrev.com/327068

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 # running overnight and removing outdated bugs/suppressions.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 76 matching lines @@
    Memcheck:Leak
    fun:_Znw*
    fun:_ZNK11AEEventImpl9duplicateEv
    fun:AESendMessage
    fun:_ZL35HIToolboxLSNotificationCallbackFunc18LSNotificationCodedPKvPK7__LSASNS1_11LSSessionIDS1_
    fun:_ZL48LSScheduleNotificationReceiveMessageCallbackFuncP12__CFMachPortPvlS1_
    fun:__CFMachPortPerform
    fun:__CFRunLoopRun
    ...
 }
+{
+   # See also http://openradar.appspot.com/20698633
+   bug_481286
+   Memcheck:Leak
+   ...
+   fun:_ZN8Security13PluginSession6mallocEm
+   fun:_Z20CL_extractCSSMKeyNSSRK33cssm_x509_subject_public_key_infoRN8Security9AllocatorEPK11DecodedCert
+}
 # Intentional leaks in AppKit, for an OS-level cache. Only appear on the first
 # run of each reboot.  See also issues 105525, 257276, 340847.
 {
    bug_257276_b
    Memcheck:Leak
    fun:malloc_zone_malloc
    ...
    fun:setCursorFromBundle
    fun:CoreCursorSet
    fun:-[NSCursor set]
@@ skipping 166 matching lines @@
 }
 {
    bug_464850
    Memcheck:Uninitialized
    fun:_ZN2v88internal9ExitFrame23GetStateForFramePointerEPhPNS0_10StackFrame5StateE
    fun:_ZN2v88internal18StackFrameIterator5ResetEPNS0_14ThreadLocalTopE
    fun:_ZN2v88internal18StackFrameIteratorC2EPNS0_7IsolateE
    fun:_ZN2v88internal18StackFrameIteratorC1EPNS0_7IsolateE
    fun:_ZN2v88internal7Isolate11FindHandlerEv
 }