Break up SkLazyPixelRef functionally into class hierarchy.

src/core/SkBitmap.cpp

Index: src/core/SkBitmap.cpp
diff --git a/src/core/SkBitmap.cpp b/src/core/SkBitmap.cpp
index bff08801fc1cf069ed8ada3607d7bcd8dfb5117d..2fae75ae3841dd39d53c305ee83f70b8ae806fe5 100644
--- a/src/core/SkBitmap.cpp
+++ b/src/core/SkBitmap.cpp
@@ -11,6 +11,7 @@
 #include "SkColorPriv.h"
 #include "SkDither.h"
 #include "SkFlattenable.h"
+#include "SkImagePriv.h"
 #include "SkMallocPixelRef.h"
 #include "SkMask.h"
 #include "SkOrderedReadBuffer.h"
@@ -332,6 +333,11 @@ BAD_CONFIG:
     return false;
 }
 
+bool SkBitmap::setConfig(const SkImageInfo& info, size_t rowBytes) {
+    return this->setConfig(SkImageInfoToBitmapConfig(info), info.fWidth,
+                           info.fHeight, rowBytes, info.fAlphaType);
+}
+
 bool SkBitmap::setAlphaType(SkAlphaType alphaType) {
     if (!validate_alphaType(this->config(), alphaType, &alphaType)) {
         return false;