Disable coverage counting by default

Bug: skia:
Change-Id: Iacb4cb3e409c6abdd25319ec0884ef673fb04cec
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201101
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/tools/flags/SkCommonFlags.cpp b/tools/flags/SkCommonFlags.cpp
index be569f8..dfacdbe 100644
--- a/tools/flags/SkCommonFlags.cpp
+++ b/tools/flags/SkCommonFlags.cpp
@@ -161,7 +161,7 @@
 
 DEFINE_bool(noGS, false, "Disables support for geometry shaders.");
 
-DEFINE_string(pr, "all",
+DEFINE_string(pr, "",
               "Set of enabled gpu path renderers. Defined as a list of: "
               "[~]none [~]dashline [~]nvpr [~]ccpr [~]aahairline [~]aaconvex [~]aalinearizing "
               "[~]small [~]tess] [~]all");