Valgrind: Widen a few existing suppressions and add a few new ones for HitTests and Mac flakiness.

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 # running overnight and removing outdated bugs/suppressions.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 2473 matching lines @@
    fun:calloc
    fun:_ZN18hb_object_header_t6createEj
    fun:_ZL16hb_object_createI9hb_face_tEPT_v
    fun:hb_face_create_for_tables
    fun:_ZN3gfx12_GLOBAL__N_118CreateHarfBuzzFaceEP10SkTypeface
    fun:_ZN3gfx12_GLOBAL__N_118CreateHarfBuzzFontEP10SkTypefacei
    fun:_ZN3gfx18RenderTextHarfBuzz8ShapeRunEPNS_8internal15TextRunHarfBuzzE
    fun:_ZN3gfx18RenderTextHarfBuzz12EnsureLayoutEv
    fun:_ZN3gfx41RenderTextTest_HarfBuzz_RunDirection_Test8TestBodyEv
 }
+{
+   bug_416957
+   Memcheck:Leak
+   fun:_Znw*
+   fun:_ZN9__gnu_cxx13new_allocatorISt13_Rb_tree_nodeISt4pairIKPKN15tracked_objects6BirthsENS3_9DeathDataEEEE8allocateEmPKv
+   fun:_ZNSt8_Rb_treeIPKN15tracked_objects6BirthsESt4pairIKS3_NS0_9DeathDataEESt10_Select1stIS7_ESt4lessIS3_ESaIS7_EE11_M_get_nodeEv
+   fun:_ZNSt8_Rb_treeIPKN15tracked_objects6BirthsESt4pairIKS3_NS0_9DeathDataEESt10_Select1stIS7_ESt4lessIS3_ESaIS7_EE14_M_create_nodeERKS7_
+   fun:_ZNSt8_Rb_treeIPKN15tracked_objects6BirthsESt4pairIKS3_NS0_9DeathDataEESt10_Select1stIS7_ESt4lessIS3_ESaIS7_EE9_M_insertEPSt18_Rb_tree_node_baseSF_RKS7_
+   fun:_ZNSt8_Rb_treeIPKN15tracked_objects6BirthsESt4pairIKS3_NS0_9DeathDataEESt10_Select1stIS7_ESt4lessIS3_ESaIS7_EE16_M_insert_uniqueESt17_Rb_tree_iteratorIS7_ERKS7_
+   fun:_ZNSt3mapIPKN15tracked_objects6BirthsENS0_9DeathDataESt4lessIS3_ESaISt4pairIKS3_S4_EEE6insertESt17_Rb_tree_iteratorIS9_ERKS9_
+   fun:_ZNSt3mapIPKN15tracked_objects6BirthsENS0_9DeathDataESt4lessIS3_ESaISt4pairIKS3_S4_EEEixERS8_
+   fun:_ZN15tracked_objects10ThreadData11TallyADeathERKNS_6BirthsEiRKNS_13TaskStopwatchE
+   fun:_ZN15tracked_objects10ThreadData31TallyRunOnNamedThreadIfTrackingERKN4base12TrackingInfoERKNS_13TaskStopwatchE
+   fun:_ZN4base5debug13TaskAnnotator7RunTaskEPKcS3_RKNS_11PendingTaskE
+   fun:_ZN4base11MessageLoop7RunTaskERKNS_11PendingTaskE
+   fun:_ZN4base11MessageLoop21DeferOrRunPendingTaskERKNS_11PendingTaskE
+   fun:_ZN4base11MessageLoop6DoWorkEv
+}
+