Make SkBitmap::CopyTo respect requested dst color type when bitmap is texture backed.

src/core/SkBitmapDevice.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 "SkBitmapDevice.h"
 #include "SkConfig8888.h"
 #include "SkDraw.h"
@@ skipping 268 matching lines @@
             matrix.mapRect(&tmpDst, tmpSrc);
             dstPtr = &tmpDst;
         }
 
         // since we may need to clamp to the borders of the src rect within
         // the bitmap, we extract a subset.
         const SkIRect srcIR = tmpSrc.roundOut();
         if(bitmap.pixelRef()->getTexture()) {
             // Accelerated source canvas, don't use extractSubset but readPixels to get the subset.
             // This way, the pixels are copied in CPU memory instead of GPU memory.
-            bitmap.pixelRef()->readPixels(&tmpBitmap, &srcIR);
+            bitmap.pixelRef()->readPixels(&tmpBitmap, kN32_SkColorType, &srcIR);
         } else {
             if (!bitmap.extractSubset(&tmpBitmap, srcIR)) {
                 return;
             }
         }
         bitmapPtr = &tmpBitmap;
 
         // Since we did an extract, we need to adjust the matrix accordingly
         SkScalar dx = 0, dy = 0;
         if (srcIR.fLeft > 0) {
@@ skipping 87 matching lines @@
         paint.getRasterizer() ||
         paint.getPathEffect() ||
         paint.isFakeBoldText() ||
         paint.getStyle() != SkPaint::kFill_Style ||
         !SkXfermode::IsMode(paint.getXfermode(), SkXfermode::kSrcOver_Mode))
     {
         return true;
     }
     return false;
 }