disable chatting debugf

BUG=skia:
TBR=bsalomon@google.com

Review URL: https://codereview.chromium.org/974883005
diff --git a/src/effects/SkColorFilters.cpp b/src/effects/SkColorFilters.cpp
index 6f7d688..8bcd0eb 100644
--- a/src/effects/SkColorFilters.cpp
+++ b/src/effects/SkColorFilters.cpp
@@ -135,7 +135,7 @@
         // conversion here.
         SkXfermode::Coeff srcCoeff, dstCoeff;
         if (!SkXfermode::ModeAsCoeff(mode, &srcCoeff, &dstCoeff)) {
-            SkDebugf("Failing to create color filter for mode %d\n", mode);
+//            SkDebugf("Failing to create color filter for mode %d\n", mode);
             return NULL;
         }
         return SkNEW_ARGS(ModeColorFilterEffect, (c, mode));