Some improvements to reduce the number of pixels touched in generating alpha clip masks
Review URL: https://codereview.appspot.com/6828043

git-svn-id: http://skia.googlecode.com/svn/trunk@6329 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrClipMaskManager.h b/src/gpu/GrClipMaskManager.h
index d23a525..89b1ef8 100644
--- a/src/gpu/GrClipMaskManager.h
+++ b/src/gpu/GrClipMaskManager.h
@@ -128,8 +128,11 @@
                        const SkClipStack::Iter::Clip* clip,
                        const GrIRect& resultBounds);
 
-    void drawTexture(GrTexture* target,
-                     GrTexture* texture);
+    void mergeMask(GrTexture* dstMask,
+                   GrTexture* srcMask,
+                   SkRegion::Op op,
+                   const GrIRect& dstBound,
+                   const GrIRect& srcBound);
 
     void getTemp(const GrIRect& bounds, GrAutoScratchTexture* temp);