Add desired width & height to drawContext (as opposed to using the width & height of the RT)

src/effects/SkGpuBlurUtils.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuBlurUtils.h"
 
 #include "SkRect.h"
@@ skipping 337 matching lines @@
     srcTexture = nullptr;     // we don't use this from here on out
 
     if (scaleFactorX > 1 || scaleFactorY > 1) {
         // Clear one pixel to the right and below, to accommodate bilinear upsampling.
         clearRect = SkIRect::MakeXYWH(srcRect.fLeft, srcRect.fBottom, srcRect.width() + 1, 1);
         srcDrawContext->clear(&clearRect, 0x0, false);
         clearRect = SkIRect::MakeXYWH(srcRect.fRight, srcRect.fTop, 1, srcRect.height());
         srcDrawContext->clear(&clearRect, 0x0, false);
 
         SkMatrix matrix;
-        matrix.setIDiv(srcDrawContext->width(), srcDrawContext->height());
+        matrix.setIDiv(srcDrawContext->accessRenderTarget()->width(),
+                       srcDrawContext->accessRenderTarget()->height());
 
         GrPaint paint;
         paint.setGammaCorrect(gammaCorrect);
         // FIXME:  this should be mitchell, not bilinear.
         GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kBilerp_FilterMode);
         sk_sp<GrTexture> tex(srcDrawContext->asTexture());
         paint.addColorTextureProcessor(tex.get(), nullptr, matrix, params);
         paint.setPorterDuffXPFactory(SkXfermode::kSrc_Mode);
 
         SkIRect dstRect(srcRect);
         scale_irect(&dstRect, scaleFactorX, scaleFactorY);
 
         dstDrawContext->fillRectToRect(clip, paint, SkMatrix::I(),
                                        SkRect::Make(dstRect), SkRect::Make(srcRect));
 
         srcDrawContext = dstDrawContext;
         srcRect = dstRect;
         dstDrawContext.swap(tmpDrawContext);
     }
 
     return srcDrawContext;
 }
 
 }
 
 #endif