Update TSAN suppressions.

BUG=skia:2459, skia:1792
R=bsalomon@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/288533002

git-svn-id: http://skia.googlecode.com/svn/trunk@14711 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/tsan.supp b/tools/tsan.supp
index 8d97964..d87f486 100644
--- a/tools/tsan.supp
+++ b/tools/tsan.supp
@@ -4,4 +4,9 @@
 race:third_party/externals/libwebp
 
 # skia:2459  Seemingly misdiagnosed use-after-free, having something to do with software GL drivers.
-race:swrast_dri.so  # If this doesn't work, it's got to be SkGLContextHelper::init :(
+race:SkGLContextHelper::init  # We don't always get swrast_dri.so in the stack or we'd use that.
+
+# For now assume anything using SkOnce and calls on SkRefCntBase (ref, unref, unique) are safe.
+# TODO(mtklein): teach TSAN about SkOnce, SkRefCnt and SkSpinlock correctly.
+race:SkOnce
+race:SkRefCntBase