guard old apis for querying byte-size of a bitmap/imageinfo/pixmap

Now with legacy behavior for allocpixels

This was reverted, so the current CL is a "fix" on top of ...
https://skia-review.googlesource.com/c/skia/+/50980

Related update to Chrome (in preparation for this change)
https://chromium-review.googlesource.com/c/chromium/src/+/685719

Bug: skia:
Change-Id: I4b370ee7e95083ab27421f008132219c9c7b86e9
Reviewed-on: https://skia-review.googlesource.com/51341
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/src/utils/mac/SkCreateCGImageRef.cpp b/src/utils/mac/SkCreateCGImageRef.cpp
index fd55d91..1514ba6 100644
--- a/src/utils/mac/SkCreateCGImageRef.cpp
+++ b/src/utils/mac/SkCreateCGImageRef.cpp
@@ -132,7 +132,7 @@
 
     const int w = bitmap->width();
     const int h = bitmap->height();
-    const size_t s = bitmap->getSize();
+    const size_t s = bitmap->computeByteSize();
 
     // our provider "owns" the bitmap*, and will take care of deleting it
     CGDataProviderRef dataRef = CGDataProviderCreateWithData(bitmap, bitmap->getPixels(), s,