Make global use-analytic-AA bit threadsafe.

I also had to cut it down to just a global atomic bool... as a field in a global singleton accessed through instance(), it's very hard to make threadsafe.

CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Release-TSAN-Trybot

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2937

Change-Id: If80be987906dd521fbe644d1d0d577009f06d0e3
Reviewed-on: https://skia-review.googlesource.com/2937
Reviewed-by: Yuqian Li <liyuqian@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 2 insertions, 15 deletions

diff --git a/src/core/SkScan.h b/src/core/SkScan.h
index 1e3d60a290..7d513693fe 100644
--- a/src/core/SkScan.h
+++ b/src/core/SkScan.h
@@ -11,6 +11,7 @@
 
 #include "SkFixed.h"
 #include "SkRect.h"
+#include <atomic>
 
 class SkRasterClip;
 class SkRegion;
@@ -22,21 +23,7 @@ class SkPath;
 */
 typedef SkIRect SkXRect;
 
-class GlobalAAConfig {
-private:
-    GlobalAAConfig() {}
-
-public:
-    bool fUseAnalyticAA = false;
-
-    GlobalAAConfig(const GlobalAAConfig&) = delete;
-    void operator=(const GlobalAAConfig&) = delete;
-
-    static GlobalAAConfig& getInstance() {
-        static GlobalAAConfig instance;
-        return instance;
-    }
-};
+extern std::atomic<bool> gSkUseAnalyticAA;
 
 class AdditiveBlitter;