Valgrind: Remove suppressions for a fixed leak and add new suppressions for Mac memory errors.

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 # running overnight and removing outdated bugs/suppressions.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 2589 matching lines @@
    Memcheck:Unaddressable
    ...
    fun:_ZN6libyuv21ScaleARGBBilinearDownEiiiiiPKhPhiiii
    fun:_ZN6libyuv16ScaleARGBAnySizeEiiiiiiiiPKhPhiiiiNS_10FilterModeE
    fun:_ZN6libyuv9ScaleARGBEPKhiiiPhiiiiiiiNS_10FilterModeE
    fun:ARGBScale
    fun:_ZN7content20DesktopCaptureDevice4Core18OnCaptureCompletedEPN6webrtc12DesktopFrameE
    fun:_ZN6webrtc12_GLOBAL__N_117ScreenCapturerMac7CaptureERKNS_13DesktopRegionE
    fun:_ZN7content20DesktopCaptureDevice4Core9DoCaptureEv
 }
+{
+   bug_292913_a
+   Memcheck:Leak
+   fun:malloc_zone_malloc
+   fun:_CFRuntimeCreateInstance
+   fun:_ZN7TCFBaseI11TDescriptorEnwEm
+   fun:_ZNK17TDescriptorSource14CopyDescriptorEPK7__CFURL
+   fun:_ZNK17TDescriptorSource32CopySystemWideFallbackDescriptorEP6CGFontPKtl
+   fun:_ZNK17TDescriptorSource32CopySystemWideFallbackDescriptorEP6CGFontPK10__CFString7CFRange
+   fun:_ZNK12TFontCascade24CreateSystemWideFallbackEPK8__CTFontPK10__CFString7CFRange
+   fun:_ZNK12TFontCascade14CreateFallbackEPK8__CTFontPK10__CFString7CFRange
+   ...
+   fun:_ZN3gfx13RenderTextMac12EnsureLayoutEv
+}
+{
+   bug_292913_b
+   Memcheck:Uninitialized
+   fun:_ZL10AddEncHashP12EncHashTablePKhij
+   fun:_Z16BuildMacEncTablev
+   fun:_ZN15TParsingContext13GetParseProcsEv
+   fun:_ZN19TSFNTParsingContext13GetParseProcsEv
+   fun:_ZN18TCIDParsingContext13GetParseProcsEv
+   fun:_ZN16TType1OTFCIDFont20ParseCFFCIDFontDictsERK19TType1CFFDescriptorP32Type1ProtectionEvaluationContextRVt
+   fun:_ZN16TType1OTFCIDFont15ParseCFFCIDFontERK19TType1CFFDescriptorP32Type1ProtectionEvaluationContext
+   fun:_ZN16TType1OTFCIDFontC2ERK19TType1CFFDescriptor
+   fun:_ZN10TType1Font7GetFontEPK5TFont
+}