Add prescale option to deferred params

include/core/SkImage.h

Index: include/core/SkImage.h
diff --git a/include/core/SkImage.h b/include/core/SkImage.h
index c9579b610c3edaf9a1df520e15e3cd4a66874988..292060bbbd92423172f04244341f93e10fe1fe75 100644
--- a/include/core/SkImage.h
+++ b/include/core/SkImage.h
@@ -343,8 +343,13 @@ public:
 
     /** Drawing params for which a deferred texture image data should be optimized. */
     struct DeferredTextureImageUsageParams {
+        DeferredTextureImageUsageParams() : fPreScaleMipLevel(0) {}
+        DeferredTextureImageUsageParams(const SkMatrix matrix, const SkFilterQuality quality, 
+                                        int preScaleMipLevel)
+            : fMatrix(matrix), fQuality(quality), fPreScaleMipLevel(preScaleMipLevel) {}
         SkMatrix        fMatrix;
         SkFilterQuality fQuality;
+        int             fPreScaleMipLevel;
     };
 
     /**