Implement srcRect and dstRect functionality in SkBitmapSource. This is required for the "preserveAs…

include/effects/SkBitmapSource.h

Index: include/effects/SkBitmapSource.h
diff --git a/include/effects/SkBitmapSource.h b/include/effects/SkBitmapSource.h
index 138987e701bb91d0529dc3e3b9bbe7fbdbc9c2a6..699186e9f1eb6c90d5b29d251a5392f56282768f 100644
--- a/include/effects/SkBitmapSource.h
+++ b/include/effects/SkBitmapSource.h
@@ -14,6 +14,7 @@
 class SK_API SkBitmapSource : public SkImageFilter {
 public:
     explicit SkBitmapSource(const SkBitmap& bitmap);
+    SkBitmapSource(const SkBitmap& bitmap, const SkRect& srcRect, const SkRect& dstRect);
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBitmapSource)
 
@@ -25,6 +26,7 @@ protected:
 
 private:
     SkBitmap fBitmap;
+    SkRect   fSrcRect, fDstRect;
     typedef SkImageFilter INHERITED;
 };