[PaintTouchActionRects] Paint replaced hit test rects without background

There was an early-out in ReplacedPainter::Paint that would skip
painting touch-action hit test rects if the replaced element did not
also paint a background. This patch skips the early-out if there is a
hit test rect that should be painted.

This does not fully fix https://crbug.com/903480 because accelerated
canvases still do not generate the correct touch action rects.

Bug: 903480
Change-Id: If6cda7339c5a20a04fe669c4d54fae30e83debf2
Reviewed-on: https://chromium-review.googlesource.com/c/1331033Reviewed-by: Xianda Sun <sunxd@chromium.org>
Commit-Queue: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607236}

third_party/blink/renderer/core/layout/layout_object.h

@@ -1937,6 +1937,9 @@ class CORE_EXPORT LayoutObject : public ImageResourceObserver,
       return TouchAction::kTouchActionNone;
     return StyleRef().GetEffectiveTouchAction();
   }
+  bool HasEffectiveWhitelistedTouchAction() const {
+    return EffectiveWhitelistedTouchAction() != TouchAction::kTouchActionAuto;
+  }
 
   // Whether this object's Node has a blocking touch event handler on itself
   // or an ancestor.

third_party/blink/renderer/core/page/scrolling/scrolling_coordinator_test.cc

@@ -517,6 +517,20 @@ TEST_P(ScrollingCoordinatorTest, elementTouchEventHandlerPassive) {
   EXPECT_TRUE(region.IsEmpty());
 }
 
+TEST_P(ScrollingCoordinatorTest, TouchActionRectsOnImage) {
+  LoadHTML(R"HTML(
+    <img id="image" style="width: 100px; height: 100px; touch-action: none;">
+  )HTML");
+  ForceFullCompositingUpdate();
+
+  auto* layout_view = GetFrame()->View()->GetLayoutView();
+  auto* mapping = layout_view->Layer()->GetCompositedLayerMapping();
+  cc::Layer* cc_layer = mapping->ScrollingContentsLayer()->CcLayer();
+  cc::Region region = cc_layer->touch_action_region().GetRegionForTouchAction(
+      TouchAction::kTouchActionNone);
+  EXPECT_EQ(region.bounds(), gfx::Rect(8, 8, 100, 100));
+}
+
 TEST_P(ScrollingCoordinatorTest, touchEventHandlerBoth) {
   RegisterMockedHttpURLLoad("touch-event-handler-both.html");
   NavigateTo(base_url_ + "touch-event-handler-both.html");

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

@@ -226,10 +226,8 @@ void PaintInvalidator::UpdatePaintingLayer(const LayoutObject& object,
     context.painting_layer->SetNeedsPaintPhaseDescendantBlockBackgrounds();
   } else if (RuntimeEnabledFeatures::PaintTouchActionRectsEnabled()) {
     // Hit testing rects for touch action paint in the background phase.
-    if (object.EffectiveWhitelistedTouchAction() !=
-        TouchAction::kTouchActionAuto) {
+    if (object.HasEffectiveWhitelistedTouchAction())
       context.painting_layer->SetNeedsPaintPhaseDescendantBlockBackgrounds();
-    }
   }
 }
 

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

@@ -105,8 +105,16 @@ void ReplacedPainter::Paint(const PaintInfo& paint_info) {
   LayoutRect border_rect(paint_offset, layout_replaced_.Size());
 
   if (ShouldPaintBoxDecorationBackground(local_paint_info)) {
-    if (layout_replaced_.StyleRef().Visibility() == EVisibility::kVisible &&
-        layout_replaced_.HasBoxDecorationBackground()) {
+    bool should_paint_background = false;
+    if (layout_replaced_.StyleRef().Visibility() == EVisibility::kVisible) {
+      if (layout_replaced_.HasBoxDecorationBackground())
+        should_paint_background = true;
+      if (RuntimeEnabledFeatures::PaintTouchActionRectsEnabled() &&
+          layout_replaced_.HasEffectiveWhitelistedTouchAction()) {
+        should_paint_background = true;
+      }
+    }
+    if (should_paint_background) {
       if (layout_replaced_.HasLayer() &&
           layout_replaced_.Layer()->GetCompositingState() ==
               kPaintsIntoOwnBacking &&

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

@@ -37,8 +37,7 @@ void ViewPainter::PaintBoxDecorationBackground(const PaintInfo& paint_info) {
 
   bool has_touch_action_rect =
       RuntimeEnabledFeatures::PaintTouchActionRectsEnabled() &&
-      (layout_view_.EffectiveWhitelistedTouchAction() !=
-       TouchAction::kTouchActionAuto);
+      (layout_view_.HasEffectiveWhitelistedTouchAction());
   if (!layout_view_.HasBoxDecorationBackground() && !has_touch_action_rect)
     return;