A precondition for this change is to switch all resampling algorithms to medium quality (aka bilinear). Otherwise, removing ImageQualityController would lead to very expensive repaints while resizing the browser window. We did some experiments (http://jsbin.com/radoni/quiet) and medium-quality images are nearly identical to high-quality for upscale.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68

commit 2b21ab04f7543ad0a20e02a92c60400b4e8e7f68
Author: pdr <pdr@chromium.org>
Date: Thu Jul 13 01:18:19 2017

Remove ImageQualityController

ImageQualityController used heuristics to draw resizing images at a lower
quality during resizes, then snap them to high quality once resizing stops.
This was needed for performance of high-quality image scales in the past, but
is less useful today because images are never scaled with a high quality filter.

This patch completely removes the ImageQualityController which has the
following benefits:
1) One less virtual on ImageResourceObserver.
2) No more visual snap as image quality changes ( https://crbug.com/503040 ).
3) A call removed from LayoutBoxModelObject::WillBeDestroyed.
4) Much complexity removed.

[1] https://chromium-review.googlesource.com/c/541609/

Bug:  503040 ,  734215 
Change-Id: I6552767925887b3154a99339976a4b624e64bac5
Reviewed-on: https://chromium-review.googlesource.com/567564
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486197}
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/BUILD.gn
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/layout/BUILD.gn
[delete] https://crrev.com/b38c2a973dde008cd590c43141ce71351a2a3a5f/third_party/WebKit/Source/core/layout/ImageQualityController.cpp
[delete] https://crrev.com/b38c2a973dde008cd590c43141ce71351a2a3a5f/third_party/WebKit/Source/core/layout/ImageQualityController.h
[delete] https://crrev.com/b38c2a973dde008cd590c43141ce71351a2a3a5f/third_party/WebKit/Source/core/layout/ImageQualityControllerTest.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/layout/LayoutBoxModelObjectTest.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/layout/LayoutBoxTest.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/layout/LayoutEmbeddedContentTest.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/layout/LayoutObject.h
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/layout/svg/LayoutSVGImage.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/loader/resource/ImageResourceObserver.h
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/paint/BoxPainter.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/paint/ImagePainter.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/paint/NinePieceImagePainter.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/paint/SVGImagePainter.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/style/ComputedStyle.cpp
[modify] https://crrev.com/2b21ab04f7543ad0a20e02a92c60400b4e8e7f68/third_party/WebKit/Source/core/style/ComputedStyle.h

This stuck!

\o/