unify peekPixels around pixmap parameter

gm/blend.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 
 DEF_SIMPLE_GM(blend, canvas, 300, 100) {
@@ skipping 18 matching lines @@
         p.setColor(SK_ColorRED);
         canvas->drawRect(SkRect::MakeXYWH(2,0,1,1), p);
         canvas->saveLayerAlpha(nullptr, 0xFC);
             p.setColor(sk_tool_utils::color_to_565(0xFF008000));
             canvas->drawRect(SkRect::MakeXYWH(2,0,1,1), p);
         canvas->restore();
     canvas->restore();
 
     // Print out the colors in each block (if we're looking at 8888 raster).
     if (canvas->imageInfo().colorType() == kN32_SkColorType) {
-        if (const SkPMColor* px = (const SkPMColor*)canvas->peekPixels(nullptr, nullptr)) {
+        SkPixmap pmap;
+        if (const SkPMColor* px = canvas->peekPixels(&pmap) ? pmap.addr32() : nullptr) {
             p.setColor(SK_ColorWHITE);
             for (int i = 0; i < 3; i++) {
                 SkPMColor c = px[i * 100];
                 SkString text = SkStringPrintf("0x%08x", c);
                 canvas->drawText(text.c_str(), text.size(), i * 100.0f + 20.0f, 50.0f, p);
             }
         }
     }
 }