Root layer scrolling: set correct size for document's main GraphicsLayer.

The main GraphicsLayer of a composited scroller should be the size of the
scroller's frame.  Report this size in PaintLayer::boundingBoxForCompositing
and update ViewPainter to use the same rect when painting the background fill.

This fixes placement of scrollbar layers in RTL documents, which were confused
by a bogus m_offsetFromLayoutObject because the rect returned by
LayoutView::documentRect is relative to the scroll origin.

This patch makes compositing/rtl/rtl-overflow-invalidation.html pass (discovered
through flag-specific expectations!)

Sadly we regress several repaint-tracking tests due to the new invalidation in
FrameView::viewportSizeChanged.  These will need flag-specific baselines (not
yet implemented) at least until http://crbug.com/568847 is addressed.

BUG=542432

Review URL: https://codereview.chromium.org/1472083006

Cr-Commit-Position: refs/heads/master@{#367034}

third_party/WebKit/LayoutTests/FlagExpectations/root-layer-scrolls

@@ -92,7 +92,6 @@ compositing/rtl/rtl-iframe-fixed-overflow-scrolled.html [ Failure ]
 compositing/rtl/rtl-iframe-fixed-overflow.html [ Failure ]
 compositing/rtl/rtl-iframe-fixed.html [ Failure ]
 compositing/rtl/rtl-iframe-relative.html [ Failure ]
-compositing/rtl/rtl-overflow-invalidation.html [ Failure ]
 compositing/scrollbars/custom-composited-different-track-parts.html [ Failure ]
 compositing/squashing/iframe-inside-squashed-layer.html [ Failure ]
 compositing/squashing/remove-squashed-layer-plus-move.html [ Failure ]
@@ -398,6 +397,12 @@ fast/repaint/window-resize-background-image-non-fixed.html [ Failure ]
 fast/repaint/window-resize-media-query.html [ Failure ]
 fast/repaint/window-resize-no-layout-change1.html [ Failure ]
 fast/repaint/window-resize-no-layout-change2.html [ Failure ]
+fast/repaint/window-resize-percent-html.html [ Failure ]
+fast/repaint/window-resize-percent-width-height.html [ Failure ]
+fast/repaint/window-resize-positioned-bottom.html [ Failure ]
+fast/repaint/window-resize-positioned-percent-top.html [ Failure ]
+fast/repaint/window-resize-vertical-writing-mode.html [ Failure ]
+fast/repaint/window-resize-viewport-percent.html [ Failure ]
 fast/replaced/border-radius-clip.html [ Failure ]
 fast/scroll-behavior/main-frame-element-scroll.html [ Failure ]
 fast/scroll-behavior/main-frame-element-scrollBy.html [ Failure ]
@@ -483,12 +488,14 @@ scrollbars/custom-scrollbar-changing-style.html [ Failure ]
 scrollingcoordinator/non-fast-scrollable-visibility-change.html [ Failure ]
 svg/as-object/deep-nested-embedded-svg-size-changes-no-layout-triggers-1.html [ Failure ]
 svg/as-object/deep-nested-embedded-svg-size-changes-no-layout-triggers-2.html [ Failure ]
+svg/as-object/embedded-svg-size-changes-no-layout-triggers.html [ Failure ]
 svg/as-object/nested-embedded-svg-size-changes-no-layout-triggers-1.html [ Failure ]
 svg/as-object/nested-embedded-svg-size-changes-no-layout-triggers-2.html [ Failure ]
 svg/custom/getscreenctm-in-scrollable-svg-area.xhtml [ Failure ]
 svg/custom/junk-data.svg [ Failure ]
 svg/custom/load-non-wellformed.svg [ Failure ]
 svg/custom/missing-xlink.svg [ Failure ]
+svg/custom/object-sizing-no-width-height-change-content-box-size.xhtml [ Failure ]
 svg/custom/path-bad-data.svg [ Failure ]
 svg/custom/scrolling-embedded-svg-file-image-repaint-problem.html [ Failure ]
 svg/custom/text-xy-updates-SVGList.xhtml [ Failure ]

third_party/WebKit/Source/core/frame/FrameView.cpp

@@ -1253,6 +1253,17 @@ void FrameView::removeViewportConstrainedObject(LayoutObject* object)
 
 void FrameView::viewportSizeChanged(bool widthChanged, bool heightChanged)
 {
+    if (m_frame->settings() && m_frame->settings()->rootLayerScrolls()) {
+        // The background must be repainted when the FrameView is resized, even if the initial
+        // containing block does not change (so we can't rely on layout to issue the invalidation).
+        // This is because the background fills the main GraphicsLayer, which takes the size of the
+        // layout viewport.
+        // TODO(skobes): Paint non-fixed backgrounds into the scrolling contents layer and avoid
+        // this invalidation (http://crbug.com/568847).
+        if (LayoutView* lv = layoutView())
+            lv->setShouldDoFullPaintInvalidation();
+    }
+
     if (!hasViewportConstrainedObjects())
         return;
 

third_party/WebKit/Source/core/paint/PaintLayer.cpp

@@ -51,6 +51,7 @@
 #include "core/frame/DeprecatedScheduleStyleRecalcDuringLayout.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
+#include "core/frame/Settings.h"
 #include "core/html/HTMLFrameElement.h"
 #include "core/layout/HitTestRequest.h"
 #include "core/layout/HitTestResult.h"
@@ -2212,8 +2213,8 @@ LayoutRect PaintLayer::boundingBoxForCompositing(const PaintLayer* ancestorLayer
     if (this != ancestorLayer && !hasVisibleContent() && !hasVisibleDescendant())
         return LayoutRect();
 
-    // The root layer is always just the size of the document.
-    if (isRootLayer())
+    // Without composited scrolling, the root layer is the size of the document.
+    if (isRootLayer() && !needsCompositedScrolling())
         return LayoutRect(m_layoutObject->view()->documentRect());
 
     // The layer created for the LayoutFlowThread is just a helper for painting and hit-testing,

third_party/WebKit/Source/core/paint/ViewPainter.cpp

@@ -55,7 +55,8 @@ void ViewPainter::paintBoxDecorationBackground(const PaintInfo& paintInfo)
     if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(context, m_layoutView, DisplayItem::BoxDecorationBackground, LayoutPoint()))
         return;
 
-    IntRect documentRect = m_layoutView.documentRect();
+    // The background fill rect is the size of the LayoutView's main GraphicsLayer.
+    IntRect backgroundRect = pixelSnappedIntRect(m_layoutView.layer()->boundingBoxForCompositing());
     const Document& document = m_layoutView.document();
     const FrameView& frameView = *m_layoutView.frameView();
     bool isMainFrame = !document.ownerElement();
@@ -65,14 +66,14 @@ void ViewPainter::paintBoxDecorationBackground(const PaintInfo& paintInfo)
     Color rootBackgroundColor = m_layoutView.style()->visitedDependentColor(CSSPropertyBackgroundColor);
     const LayoutObject* rootObject = document.documentElement() ? document.documentElement()->layoutObject() : nullptr;
 
-    LayoutObjectDrawingRecorder recorder(context, m_layoutView, DisplayItem::BoxDecorationBackground, documentRect, LayoutPoint());
+    LayoutObjectDrawingRecorder recorder(context, m_layoutView, DisplayItem::BoxDecorationBackground, backgroundRect, LayoutPoint());
 
     // Special handling for print economy mode.
     bool forceBackgroundToWhite = BoxPainter::shouldForceWhiteBackgroundForPrintEconomy(m_layoutView.styleRef(), document);
     if (forceBackgroundToWhite) {
         // If for any reason the view background is not transparent, paint white instead, otherwise keep transparent as is.
         if (paintsBaseBackground || rootBackgroundColor.alpha() || m_layoutView.style()->backgroundLayers().image())
-            context.fillRect(documentRect, Color::white, SkXfermode::kSrc_Mode);
+            context.fillRect(backgroundRect, Color::white, SkXfermode::kSrc_Mode);
         return;
     }
 
@@ -84,7 +85,7 @@ void ViewPainter::paintBoxDecorationBackground(const PaintInfo& paintInfo)
     // we need to apply inverse transform on the document rect to get to the root element space.
     bool backgroundRenderable = true;
     TransformationMatrix transform;
-    IntRect paintRect = documentRect;
+    IntRect paintRect = backgroundRect;
     if (!rootObject || !rootObject->isBox()) {
         backgroundRenderable = false;
     } else if (rootObject->hasLayer()) {
@@ -98,16 +99,16 @@ void ViewPainter::paintBoxDecorationBackground(const PaintInfo& paintInfo)
             backgroundRenderable = false;
         } else {
             bool isClamped;
-            paintRect = transform.inverse().projectQuad(FloatQuad(documentRect), &isClamped).enclosingBoundingBox();
+            paintRect = transform.inverse().projectQuad(FloatQuad(backgroundRect), &isClamped).enclosingBoundingBox();
             backgroundRenderable = !isClamped;
         }
     }
 
     if (!backgroundRenderable) {
         if (baseBackgroundColor.alpha())
-            context.fillRect(documentRect, baseBackgroundColor, shouldClearCanvas ? SkXfermode::kSrc_Mode : SkXfermode::kSrcOver_Mode);
+            context.fillRect(backgroundRect, baseBackgroundColor, shouldClearCanvas ? SkXfermode::kSrc_Mode : SkXfermode::kSrcOver_Mode);
         else if (shouldClearCanvas)
-            context.fillRect(documentRect, Color(), SkXfermode::kClear_Mode);
+            context.fillRect(backgroundRect, Color(), SkXfermode::kClear_Mode);
         return;
     }
 
@@ -126,15 +127,15 @@ void ViewPainter::paintBoxDecorationBackground(const PaintInfo& paintInfo)
 
     if (shouldDrawBackgroundInSeparateBuffer) {
         if (baseBackgroundColor.alpha())
-            context.fillRect(documentRect, baseBackgroundColor, shouldClearCanvas ? SkXfermode::kSrc_Mode : SkXfermode::kSrcOver_Mode);
+            context.fillRect(backgroundRect, baseBackgroundColor, shouldClearCanvas ? SkXfermode::kSrc_Mode : SkXfermode::kSrcOver_Mode);
         context.beginLayer();
     }
 
     Color combinedBackgroundColor = shouldDrawBackgroundInSeparateBuffer ? rootBackgroundColor : baseBackgroundColor.blend(rootBackgroundColor);
     if (combinedBackgroundColor.alpha())
-        context.fillRect(documentRect, combinedBackgroundColor, (shouldDrawBackgroundInSeparateBuffer || shouldClearCanvas) ? SkXfermode::kSrc_Mode : SkXfermode::kSrcOver_Mode);
+        context.fillRect(backgroundRect, combinedBackgroundColor, (shouldDrawBackgroundInSeparateBuffer || shouldClearCanvas) ? SkXfermode::kSrc_Mode : SkXfermode::kSrcOver_Mode);
     else if (shouldClearCanvas && !shouldDrawBackgroundInSeparateBuffer)
-        context.fillRect(documentRect, Color(), SkXfermode::kClear_Mode);
+        context.fillRect(backgroundRect, Color(), SkXfermode::kClear_Mode);
 
     for (auto it = reversedPaintList.rbegin(); it != reversedPaintList.rend(); ++it) {
         ASSERT((*it)->clip() == BorderFillBox);