add peekPixels to SkCanvas and SkSurface

gm/bitmapcopy.cpp

Index: gm/bitmapcopy.cpp
diff --git a/gm/bitmapcopy.cpp b/gm/bitmapcopy.cpp
index 928b4037c136000d0d9910102c37ad51c5a4a31d..f210b4aa5e0870e2c55682924c5e93831797be95 100644
--- a/gm/bitmapcopy.cpp
+++ b/gm/bitmapcopy.cpp
@@ -62,14 +62,14 @@ protected:
 
     virtual void onDraw(SkCanvas* canvas) {
         SkPaint paint;
-        SkScalar horizMargin(SkIntToScalar(10));
-        SkScalar vertMargin(SkIntToScalar(10));
+        SkScalar horizMargin = 10;
+        SkScalar vertMargin = 10;
 
-        SkBitmapDevice devTmp(SkBitmap::kARGB_8888_Config, 40, 40, false);
-        SkCanvas canvasTmp(&devTmp);
+        SkBitmap src;
+        src.allocN32Pixels(40, 40);
+        SkCanvas canvasTmp(src);
 
         draw_checks(&canvasTmp, 40, 40);
-        SkBitmap src = canvasTmp.getTopDevice()->accessBitmap(false);
 
         for (unsigned i = 0; i < NUM_CONFIGS; ++i) {
             if (!src.deepCopyTo(&fDst[i], gConfigs[i])) {