I'm trying to remember the broader use case here.  We need to convert from an SkImage in one color space into an SkImage in another color space because...

There are different scenarios. For one, the image bitmap source may be in color space X, but the ImageBitmapOptions may indicate that the target image bitmap is expected to be in color space Y. If image bitmap source uses an SkImage as the storage, we can simply add a method to the image bitmap source that calls SkImage::makeColorSpace() on the SkImage object and returns one with the desired color space. Afterward, we can apply other features asked in ImageBitmapOptions over the color converted SkImage.

Got it.  This manipulation of ImageBitmaps is exposed in the Canvas API?

Yes. See https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/imagebitmap/ImageBitmapOptions.idl?q=imagebitmapoptions.idl&dr. P3 and Rec2020 will be added soon.

colorSpaceConversion creation attribute specifies the desired color space of the ImageBitmap object, to which the image bitmap source must be color converted.

SkImage::readPixels now supports correct color conversion and is the desired way to do so.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/70d96a8266f71bb56e1cbbc54689b59d8eab5d40

commit 70d96a8266f71bb56e1cbbc54689b59d8eab5d40
Author: Reza.Zakerinasab <zakerinasab@chromium.org>
Date: Tue Jun 13 19:14:11 2017

Refactor ImageBitmap

This CL refactors ImageBitmap. It was essentially started to fix
ImageBitmap constructor from ImageData which was not correctly handling
ColorSpaceConversion attribute passed in ImageBitmapOptions. During the
developement it gradually extended to improving other constructors too.
(This CL is moved from Rietveld codereview.chromium.org/2845193002.)

BUG= 714649 , 683307 ,627855, 715264 , 715239 , 714364 , 686862 , 665919 

Change-Id: Iecba66e8764b189a4f5130096b4b5a19a9a32cae
Reviewed-on: https://chromium-review.googlesource.com/527690
Commit-Queue: Mohammad Reza Zakerinasab <zakerinasab@chromium.org>
Reviewed-by: Justin Novosad <junov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#479093}
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage-expected.txt
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/LayoutTests/fast/canvas/canvas-createImageBitmap-out-of-bounds-src-expected.html
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/LayoutTests/fast/canvas/canvas-createImageBitmap-recursive.html
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/LayoutTests/fast/canvas/webgl/resources/tex-image-and-sub-image-image-bitmap-utils.js
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/Source/core/frame/ImageBitmap.cpp
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/Source/core/frame/ImageBitmapTest.cpp
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/Source/core/html/ImageData.cpp
[modify] https://crrev.com/70d96a8266f71bb56e1cbbc54689b59d8eab5d40/third_party/WebKit/Source/core/html/ImageData.h

This is done for now as we have replaced readPixels() with makeColorSpace() wherever possible.