use skia cgimage->bitmap routine

skia/ext/skia_utils_mac.mm

Index: skia/ext/skia_utils_mac.mm
diff --git a/skia/ext/skia_utils_mac.mm b/skia/ext/skia_utils_mac.mm
index 57fb7076ba219c4b5ccefb292200c69b5d644638..7bb6964917836e176421d9f06f1e71d481e378e1 100644
--- a/skia/ext/skia_utils_mac.mm
+++ b/skia/ext/skia_utils_mac.mm
@@ -184,31 +184,10 @@ NSColor* SkColorToSRGBNSColor(SkColor color) {
 }
 
 SkBitmap CGImageToSkBitmap(CGImageRef image) {
-  if (!image)
-    return SkBitmap();
-
-  int width = CGImageGetWidth(image);
-  int height = CGImageGetHeight(image);
-
-  std::unique_ptr<SkCanvas> canvas(skia::CreatePlatformCanvas(
-      nullptr, width, height, false, RETURN_NULL_ON_FAILURE));
-  ScopedPlatformPaint p(canvas.get());
-  CGContextRef context = p.GetNativeDrawingContext();
-
-  // We need to invert the y-axis of the canvas so that Core Graphics drawing
-  // happens right-side up. Skia has an upper-left origin and CG has a lower-
-  // left one.
-  CGContextScaleCTM(context, 1.0, -1.0);
-  CGContextTranslateCTM(context, 0, -height);
-
-  // We want to copy transparent pixels from |image|, instead of blending it
-  // onto uninitialized pixels.
-  CGContextSetBlendMode(context, kCGBlendModeCopy);
-
-  CGRect rect = CGRectMake(0, 0, width, height);
-  CGContextDrawImage(context, rect, image);
-
-  return skia::ReadPixels(canvas.get());
+  SkBitmap bm;
+  if (image)
+    (void)SkCreateBitmapFromCGImage(&bm, image);

[dcheng, 2016/12/21 20:54:51]

I don't think I'm an owner for this code, but in Chrome:
- I think we usually don't explicitly ignore a return value unless it's marked
WARN_UNUSED_RESULT
- If we do want to explicit ignore it, we use base::ignore_result (not to be
confused with base::IgnoreResult... ugh, naming) to make it obvious.

[reed1, 2016/12/21 21:00:26]

Done.

+  return bm;
 }
 
 SkBitmap NSImageToSkBitmapWithColorSpace(