Add optional sw generated path coverage mask caching

src/gpu/GrSWMaskHelper.h

Index: src/gpu/GrSWMaskHelper.h
diff --git a/src/gpu/GrSWMaskHelper.h b/src/gpu/GrSWMaskHelper.h
index f2bb34b30c090df98c8c365ceae0e472b96a945b..46520a91bea34bc9cd16e13759166fc1d5f408fc 100644
--- a/src/gpu/GrSWMaskHelper.h
+++ b/src/gpu/GrSWMaskHelper.h
@@ -8,8 +8,9 @@
 #ifndef GrSWMaskHelper_DEFINED
 #define GrSWMaskHelper_DEFINED
 
-#include "SkAutoPixmapStorage.h"
 #include "GrColor.h"
+#include "GrTextureProvider.h"
+#include "SkAutoPixmapStorage.h"
 #include "SkBitmap.h"
 #include "SkDraw.h"
 #include "SkMatrix.h"
@@ -66,36 +67,37 @@ public:
         fPixels.erase(SkColorSetARGB(alpha, 0xFF, 0xFF, 0xFF));
     }
 
+
+    enum class TextureType {
+        kExactFit,
+        kApproximateFit
+    };
+
     // Canonical usage utility that draws a single path and uploads it
     // to the GPU. The result is returned.
     static GrTexture* DrawShapeMaskToTexture(GrTextureProvider*,
                                              const GrShape&,
                                              const SkIRect& resultBounds,
                                              bool antiAlias,
+                                             TextureType,
                                              const SkMatrix* matrix);
 
-    // This utility routine is used to add a shape's mask to some other draw.
-    // The GrClipStackClip uses it to accumulate clip masks while the
-    // GrSoftwarePathRenderer uses it to fulfill a drawPath call.
-    // It draws with "texture" as a path mask into "target" using "rect" as
-    // geometry and the current drawState. The current drawState is altered to
-    // accommodate the mask.
-    // Note that this method assumes that the GrPaint::kTotalStages slot in
-    // the draw state can be used to hold the mask texture stage.
-    // This method is really only intended to be used with the
-    // output of DrawPathMaskToTexture.
+    // This utility draws a path mask generated by DrawShapeMaskToTexture using a provided paint.
+    // The rectangle is drawn in device space. The 'viewMatrix' will be used to ensure the correct
+    // local coords are provided to any fragment processors in the paint.
     static void DrawToTargetWithShapeMask(GrTexture* texture,
                                           GrDrawContext*,
                                           const GrPaint& paint,
                                           const GrUserStencilSettings& userStencilSettings,
                                           const GrClip&,
                                           const SkMatrix& viewMatrix,
-                                          const SkIRect& rect);
+                                          const SkIPoint& textureOriginInDeviceSpace,
+                                          const SkIRect& deviceSpaceRectToDraw);
 
 private:
     // Helper function to get a scratch texture suitable for capturing the
     // result (i.e., right size & format)
-    GrTexture* createTexture();
+    GrTexture* createTexture(TextureType);
 
     GrTextureProvider*  fTexProvider;
     SkMatrix            fMatrix;