Valgrind is not a fan of uninitialized Src pixels.
Valgrind is not a fan of uninitialized Src pixels.

E.g. search for ==31875== in this log:

https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-Valgrind/builds/774/steps/nanobench/logs/stdio

BUG=skia:4818
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1601093003

Review URL: https://codereview.chromium.org/1601093003

HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,qrealka/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,rubenvb/skia,qrealka/skia-hc,aosp-mirror/platform_external_skia,qrealka/skia-hc,qrealka/skia-hc,aosp-mirror/platform_external_skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,google/skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,google/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,tmpvar/skia.cc,google/skia,aosp-mirror/platform_external_skia,tmpvar/skia.cc,Hikari-no-Tenshi/android_external_skia,qrealka/skia-hc,HalCanary/skia-hc,rubenvb/skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,tmpvar/skia.cc,google/skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,google/skia,aosp-mirror/platform_external_skia,qrealka/skia-hc,tmpvar/skia.cc,qrealka/skia-hc,aosp-mirror/platform_external_skia,tmpvar/skia.cc,aosp-mirror/platform_external_skia,google/skia,tmpvar/skia.cc,tmpvar/skia.cc,rubenvb/skia,rubenvb/skia,google/skia,tmpvar/skia.cc,rubenvb/skia,rubenvb/skia,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,qrealka/skia-hc,aosp-mirror/platform_external_skia,tmpvar/skia.cc