Fix texture allocation in SWMaskHelper

src/gpu/GrSWMaskHelper.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrSWMaskHelper_DEFINED
 #define GrSWMaskHelper_DEFINED
 
@@ skipping 45 matching lines @@
 
     // Draw a single path into the accumuation bitmap using the specified op
     void draw(const SkPath& path, const SkStrokeRec& stroke, SkRegion::Op op,
               bool antiAlias, uint8_t alpha);
 
     // Helper function to get a scratch texture suitable for capturing the
     // result (i.e., right size & format)
     bool getTexture(GrAutoScratchTexture* texture);
 
     // Move the mask generation results from the internal bitmap to the gpu.
-    // The space outside of the mask is cleared using "alpha"
-    void toTexture(GrTexture* texture, uint8_t alpha);
+    void toTexture(GrTexture* texture);
 
     // Reset the internal bitmap
     void clear(uint8_t alpha) {
         fBM.eraseColor(SkColorSetARGB(alpha, alpha, alpha, alpha));
     }
 
     // Canonical usage utility that draws a single path and uploads it
     // to the GPU. The result is returned in "result".
     static GrTexture* DrawPathMaskToTexture(GrContext* context,
                                             const SkPath& path,
@@ skipping 21 matching lines @@
     GrContext*      fContext;
     SkMatrix        fMatrix;
     SkBitmap        fBM;
     SkDraw          fDraw;
     SkRasterClip    fRasterClip;
 
     typedef GrNoncopyable INHERITED;
 };
 
 #endif // GrSWMaskHelper_DEFINED