Allow iframes to paint the base background for color-scheme.

According to spec[1], a mismatching used color-scheme for embedding
iframe element and iframe document root element should cause an opaque
canvas background for the color-scheme to be painted behind the document
background.

Modify the ViewPainter to allow painting the base background in an
iframe for these cases.

Bug: 1058822
Change-Id: I0097d8207c2f697367c477b795bfb2443ebd5cb2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2418322
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Reviewed-by: Stefan Zager <szager@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809508}

third_party/blink/renderer/core/layout/layout_view.cc

@@ -870,7 +870,7 @@ void LayoutView::UpdateFromStyle() {
   LayoutBlockFlow::UpdateFromStyle();
 
   // LayoutView of the main frame is responsible for painting base background.
-  if (GetDocument().IsInMainFrame())
+  if (GetFrameView()->ShouldPaintBaseBackgroundColor())
     SetHasBoxDecorationBackground(true);
 }
 

third_party/blink/renderer/core/paint/view_painter.cc

@@ -43,7 +43,7 @@ void ViewPainter::PaintRootGroup(const PaintInfo& paint_info,
                                  const Document& document,
                                  const DisplayItemClient& client,
                                  const PropertyTreeStateOrAlias& state) {
-  if (!document.IsInMainFrame())
+  if (!layout_view_.GetFrameView()->ShouldPaintBaseBackgroundColor())
     return;
   bool should_clear_canvas =
       document.GetSettings() &&
@@ -245,7 +245,7 @@ void ViewPainter::PaintRootElementGroup(
 
   const Document& document = layout_view_.GetDocument();
   const LocalFrameView& frame_view = *layout_view_.GetFrameView();
-  bool paints_base_background = document.IsInMainFrame() &&
+  bool paints_base_background = frame_view.ShouldPaintBaseBackgroundColor() &&
                                 (frame_view.BaseBackgroundColor().Alpha() > 0);
   Color base_background_color =
       paints_base_background ? frame_view.BaseBackgroundColor() : Color();

third_party/blink/web_tests/TestExpectations

@@ -1332,9 +1332,6 @@ crbug.com/1012289 external/wpt/css/css-lists/list-style-type-string-005b.html [
 crbug.com/995106 external/wpt/css/css-pseudo/first-letter-exclude-inline-marker.html [ Failure ]
 crbug.com/995106 external/wpt/css/css-pseudo/first-letter-exclude-inline-child-marker.html [ Failure ]
 
-crbug.com/1058822 external/wpt/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-iframe-background-mismatch-alpha.html [ Failure ]
-crbug.com/1058822 external/wpt/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-iframe-background-mismatch-opaque.html [ Failure ]
-crbug.com/1058822 external/wpt/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-iframe-background-mismatch-opaque-cross-origin.sub.html [ Failure ]
 crbug.com/929098 external/wpt/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-change-checkbox.html [ Failure ]
 crbug.com/929098 virtual/dark-color-scheme/external/wpt/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-change-checkbox.html [ Pass ]