[editing] Don't go into UA shadow in Find{For,Back}wardInlineContents

Before this patch, for HTML like "<select></select>foo",

  Element* select = GetDocument().QuerySelector("select");
  TextOffsetMapping::FindForwardInlineContents(
      PositionInFlatTree::BeforeNode(*select)));

would go into the shadow root of the <select>, and return

  TextOffsetMapping::InlineContents(To<LayoutBlockFlow>(
      *select->GetShadowRoot()->firstChild()->GetLayoutObject()));

This patch changes FindForwardInlineContents so that it instead returns

  TextOffsetMapping::InlineContents(
      To<LayoutBlockFlow>(*GetDocument().body()->GetLayoutObject()),
      *select->GetLayoutObject(), *select->GetLayoutObject())

just like it already happens for PositionInFlatTree::AfterNode(*select).

And analogous for FindBackwardInlineContents.

Bug: 1154430

TEST=All/ParameterizedTextOffsetMappingTest.RangeWithSelect1/0
TEST=All/ParameterizedTextOffsetMappingTest.RangeWithSelect1/1
TEST=All/ParameterizedTextOffsetMappingTest.RangeWithSelect2/0
TEST=All/ParameterizedTextOffsetMappingTest.RangeWithSelect2/1

Change-Id: Ib894e8d691f99189fc5f35f1bfa18365f4b59e4d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2566939
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832658}

third_party/blink/renderer/core/editing/text_offset_mapping.cc

@@ -290,11 +290,17 @@ TextOffsetMapping::InlineContents TextOffsetMapping::FindBackwardInlineContents(
   auto previous_skipping_text_control = [](const Node& node) -> const Node* {
     DCHECK(!EnclosingTextControl(&node));
     const Node* previous = PreviousNodeSkippingAncestors(node);
+    if (!previous)
+      return previous;
     const TextControlElement* previous_text_control =
         EnclosingTextControl(previous);
-    if (!previous_text_control)
-      return previous;
-    return previous_text_control;
+    if (previous_text_control)
+      return previous_text_control;
+    if (ShadowRoot* root = previous->ContainingShadowRoot()) {
+      if (root->IsUserAgent())
+        return root->OwnerShadowHost();
+    }
+    return previous;
   };
 
   if (const TextControlElement* last_enclosing_text_control =
@@ -334,6 +340,10 @@ TextOffsetMapping::InlineContents TextOffsetMapping::FindForwardInlineContents(
     DCHECK(!EnclosingTextControl(&node));
     if (IsTextControl(node))
       return FlatTreeTraversal::NextSkippingChildren(node);
+    if (ShadowRoot* root = node.GetShadowRoot()) {
+      if (root->IsUserAgent())
+        return FlatTreeTraversal::NextSkippingChildren(node);
+    }
     return FlatTreeTraversal::Next(node);
   };
   DCHECK(!EnclosingTextControl(next_node));

third_party/blink/renderer/core/editing/text_offset_mapping_test.cc

@@ -38,8 +38,11 @@ class ParameterizedTextOffsetMappingTest
   }
 
   std::string GetRange(const std::string& selection_text) {
-    const PositionInFlatTree position =
-        ToPositionInFlatTree(SetSelectionTextToBody(selection_text).Base());
+    return GetRange(
+        ToPositionInFlatTree(SetSelectionTextToBody(selection_text).Base()));
+  }
+
+  std::string GetRange(const PositionInFlatTree& position) {
     return GetRange(GetInlineContents(position));
   }
 
@@ -421,13 +424,41 @@ TEST_P(ParameterizedTextOffsetMappingTest, RangeWithNestedPosition) {
 }
 
 // http://crbug.com//834623
-TEST_P(ParameterizedTextOffsetMappingTest, RangeWithSelect) {
-  EXPECT_EQ(
+TEST_P(ParameterizedTextOffsetMappingTest, RangeWithSelect1) {
+  SetBodyContent("<select></select>foo");
+  Element* select = GetDocument().QuerySelector("select");
+  const auto& expected_outer =
       "^<select>"
       "<div aria-hidden=\"true\"></div>"
       "<slot name=\"user-agent-custom-assign-slot\"></slot>"
-      "</select>foo|",
-      GetRange("<select>|</select>foo"));
+      "</select>foo|";
+  const auto& expected_inner =
+      "<select>"
+      "<div aria-hidden=\"true\">^|</div>"
+      "<slot name=\"user-agent-custom-assign-slot\"></slot>"
+      "</select>foo";
+  EXPECT_EQ(expected_outer, GetRange(PositionInFlatTree::BeforeNode(*select)));
+  EXPECT_EQ(expected_inner, GetRange(PositionInFlatTree(select, 0)));
+  EXPECT_EQ(expected_outer, GetRange(PositionInFlatTree::AfterNode(*select)));
+}
+
+TEST_P(ParameterizedTextOffsetMappingTest, RangeWithSelect2) {
+  SetBodyContent("<select>bar</select>foo");
+  Element* select = GetDocument().QuerySelector("select");
+  const auto& expected_outer =
+      "^<select>"
+      "<div aria-hidden=\"true\"></div>"
+      "<slot name=\"user-agent-custom-assign-slot\"></slot>"
+      "</select>foo|";
+  const auto& expected_inner =
+      "<select>"
+      "<div aria-hidden=\"true\">^|</div>"
+      "<slot name=\"user-agent-custom-assign-slot\"></slot>"
+      "</select>foo";
+  EXPECT_EQ(expected_outer, GetRange(PositionInFlatTree::BeforeNode(*select)));
+  EXPECT_EQ(expected_inner, GetRange(PositionInFlatTree(select, 0)));
+  EXPECT_EQ(expected_outer, GetRange(PositionInFlatTree(select, 1)));
+  EXPECT_EQ(expected_outer, GetRange(PositionInFlatTree::AfterNode(*select)));
 }
 
 // http://crbug.com//832350