Add an LATC compressor to the A8 masks, and hide it behind an ifdef.

src/gpu/GrSWMaskHelper.h

Index: src/gpu/GrSWMaskHelper.h
diff --git a/src/gpu/GrSWMaskHelper.h b/src/gpu/GrSWMaskHelper.h
index 697d6f3a490c584437fe3eb43270cadcc8b8ba10..894f49c9cd7aec1404b5d8f7070e94a6d87f5320 100644
--- a/src/gpu/GrSWMaskHelper.h
+++ b/src/gpu/GrSWMaskHelper.h
@@ -65,6 +65,8 @@ public:
     // Move the mask generation results from the internal bitmap to the gpu.
     void toTexture(GrTexture* texture);
 
+    GrTexture* toLATCTexture(GrContext* ctx);
+
     // Reset the internal bitmap
     void clear(uint8_t alpha) {
         fBM.eraseColor(SkColorSetARGB(alpha, alpha, alpha, alpha));