[LayoutNG] Implement dom-snapshot inspector protocol

This patch implements dom-snapshot inspector protocol for
LayoutNG.

The offset is not implemented yet in this patch, and thus
2 more tests do not pass yet.

Bug: 636993
Change-Id: I0b57685cc6777ab8d06fbce8b5c8d935aed2648c
Reviewed-on: https://chromium-review.googlesource.com/1175758
Commit-Queue: Koji Ishii <kojii@chromium.org>
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583394}

third_party/blink/renderer/core/inspector/inspector_dom_snapshot_agent.cc

@@ -826,19 +826,19 @@ int InspectorDOMSnapshotAgent::VisitLayoutTreeNode(LayoutObject* layout_object,
   if (layout_object->IsText()) {
     LayoutText* layout_text = ToLayoutText(layout_object);
     layout_tree_node->setLayoutText(layout_text->GetText());
-    if (layout_text->HasTextBoxes()) {
+    Vector<LayoutText::TextBoxInfo> text_boxes = layout_text->GetTextBoxInfo();
+    if (!text_boxes.IsEmpty()) {
       std::unique_ptr<protocol::Array<protocol::DOMSnapshot::InlineTextBox>>
           inline_text_nodes =
               protocol::Array<protocol::DOMSnapshot::InlineTextBox>::create();
-      for (const InlineTextBox* text_box : layout_text->TextBoxes()) {
-        FloatRect local_coords_text_box_rect(text_box->FrameRect());
+      for (const LayoutText::TextBoxInfo& text_box : text_boxes) {
         FloatRect absolute_coords_text_box_rect =
-            layout_object->LocalToAbsoluteQuad(local_coords_text_box_rect)
+            layout_object->LocalToAbsoluteQuad(FloatRect(text_box.local_rect))
                 .BoundingBox();
         inline_text_nodes->addItem(
             protocol::DOMSnapshot::InlineTextBox::create()
-                .setStartCharacterIndex(text_box->Start())
-                .setNumCharacters(text_box->Len())
+                .setStartCharacterIndex(text_box.dom_start_offset)
+                .setNumCharacters(text_box.dom_length)
                 .setBoundingBox(
                     BuildRectForFloatRect(absolute_coords_text_box_rect))
                 .build());

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

@@ -238,6 +238,32 @@ void LayoutText::DeleteTextBoxes() {
   text_boxes_.DeleteLineBoxes();
 }
 
+Vector<LayoutText::TextBoxInfo> LayoutText::GetTextBoxInfo() const {
+  Vector<TextBoxInfo> results;
+  if (RuntimeEnabledFeatures::LayoutNGEnabled()) {
+    auto fragments = NGPaintFragment::InlineFragmentsFor(this);
+    if (fragments.IsInLayoutNGInlineFormattingContext()) {
+      for (const NGPaintFragment* fragment : fragments) {
+        const NGPhysicalTextFragment& text_fragment =
+            ToNGPhysicalTextFragment(fragment->PhysicalFragment());
+        results.push_back(TextBoxInfo{
+            {fragment->InlineOffsetToContainerBox().ToLayoutPoint(),
+             text_fragment.Size().ToLayoutSize()},
+            // TODO(kojii): Compute DOM offset, not text content offset.
+            text_fragment.StartOffset(),
+            text_fragment.Length()});
+      }
+      return results;
+    }
+  }
+
+  for (const InlineTextBox* text_box : TextBoxes()) {
+    results.push_back(
+        TextBoxInfo{text_box->FrameRect(), text_box->Start(), text_box->Len()});
+  }
+  return results;
+}
+
 base::Optional<FloatPoint> LayoutText::GetUpperLeftCorner() const {
   DCHECK(!IsBR());
   if (HasLegacyTextBoxes()) {

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

@@ -225,6 +225,14 @@ class CORE_EXPORT LayoutText : public LayoutObject {
   // All callers should call HasTextBoxes instead, and take NG into account.
   bool HasLegacyTextBoxes() const { return FirstTextBox(); }
 
+  // Compute the rect and offset of text boxes for this LayoutText.
+  struct TextBoxInfo {
+    LayoutRect local_rect;
+    unsigned dom_start_offset;
+    unsigned dom_length;
+  };
+  Vector<TextBoxInfo> GetTextBoxInfo() const;
+
   // Returns the Position in DOM that corresponds to the given offset in the
   // |text_| string.
   // TODO(layout-dev): Fix it when text-transform changes text length.