Add SkBitmap::readPixels() and reimplement copyTo and SkCanvas::readPixels

src/core/SkConfig8888.h

Index: src/core/SkConfig8888.h
diff --git a/src/core/SkConfig8888.h b/src/core/SkConfig8888.h
index 97a3433ad24281f289d50c3b00c708a8066c9cf7..da0cbc66882f26cdb4f039d99cc8818f1a802fb2 100644
--- a/src/core/SkConfig8888.h
+++ b/src/core/SkConfig8888.h
@@ -14,6 +14,10 @@ struct SkPixelInfo {
     SkColorType fColorType;
     SkAlphaType fAlphaType;
     size_t      fRowBytes;
+
+    static bool CopyPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
+                           const SkImageInfo& srcInfo, const void* srcPixels, size_t srcRowBytes,
+                           SkColorTable* srcCTable = NULL);
 };
 
 struct SkDstPixelInfo : SkPixelInfo {