Introduce FlatTreeTraversal::InclusiveAncestorsOf()

This patch Introduces FlatTreeTraversal::InclusiveAncestorsOf() as
|NodeTraversal|.

This patch is a preparation of the patch[1].

[1] http://crrev.com/c/737981: Introduce TextOffsetMapping to simplify
word/paragraph selection

Change-Id: I5ec0043887b0d72816bd2b0701a3e6cbe40ff28e
Reviewed-on: https://chromium-review.googlesource.com/742770
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512783}

third_party/WebKit/Source/core/dom/FlatTreeTraversal.h

@@ -129,13 +129,15 @@ class CORE_EXPORT FlatTreeTraversal {
   // |NodeTraversal|:
   //   - AncestorsOf()
   //   - DescendantsOf()
-  //   - InclusiveAncestorsOf()
   //   - InclusiveDescendantsOf()
   //   - StartsAt()
   //   - StartsAfter()
   static TraversalRange<TraversalChildrenIterator<FlatTreeTraversal>>
   ChildrenOf(const Node&);
 
+  static TraversalRange<TraversalInclusiveAncestorsIterator<FlatTreeTraversal>>
+  InclusiveAncestorsOf(const Node&);
+
  private:
   enum TraversalDirection {
     kTraversalDirectionForward,
@@ -344,6 +346,12 @@ FlatTreeTraversal::ChildrenOf(const Node& parent) {
   return TraversalRange<TraversalChildrenIterator<FlatTreeTraversal>>(&parent);
 }
 
+inline TraversalRange<TraversalInclusiveAncestorsIterator<FlatTreeTraversal>>
+FlatTreeTraversal::InclusiveAncestorsOf(const Node& node) {
+  return TraversalRange<TraversalInclusiveAncestorsIterator<FlatTreeTraversal>>(
+      &node);
+}
+
 }  // namespace blink
 
 #endif

third_party/WebKit/Source/core/dom/FlatTreeTraversalTest.cpp

@@ -330,6 +330,23 @@ TEST_F(FlatTreeTraversalTest, nextSkippingChildren) {
   EXPECT_EQ(*m1, FlatTreeTraversal::PreviousSkippingChildren(*m2));
 }
 
+TEST_F(FlatTreeTraversalTest, InclusiveAncestorsOf) {
+  SetupDocumentTree("<div><div><div id=sample></div></div></div>");
+  Element* const sample = GetDocument().getElementById("sample");
+
+  HeapVector<Member<Node>> expected_nodes;
+  for (Node* parent = sample; parent;
+       parent = FlatTreeTraversal::Parent(*parent)) {
+    expected_nodes.push_back(parent);
+  }
+
+  HeapVector<Member<Node>> actual_nodes;
+  for (Node& ancestor : FlatTreeTraversal::InclusiveAncestorsOf(*sample))
+    actual_nodes.push_back(&ancestor);
+
+  EXPECT_EQ(expected_nodes, actual_nodes);
+}
+
 // Test case for
 //  - lastWithin
 //  - lastWithinOrSelf