EXPERIMENT TextIterator built on Layout NG offset mapping

third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.h

Index: third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.h
diff --git a/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.h b/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.h
index 48d15960197d1099e7449fd7e9019c226bf81f71..90eacccc550748118c6d1bfdae10bcdf163d0a7e 100644
--- a/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.h
+++ b/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.h
@@ -7,12 +7,15 @@
 
 #include "core/dom/Text.h"
 #include "core/editing/iterators/TextIteratorBehavior.h"
+#include "core/layout/ng/inline/ng_offset_mapping_builder.h"
+#include "core/layout/ng/inline/ng_offset_mapping_result.h"
 #include "platform/heap/Handle.h"
 #include "platform/wtf/Vector.h"
 
 namespace blink {
 
 class InlineTextBox;
+class LayoutNGBlockFlow;
 class LayoutText;
 class LayoutTextFragment;
 class TextIteratorTextState;
@@ -56,6 +59,8 @@ class TextIteratorTextNodeHandler final
   size_t RestoreCollapsedTrailingSpace(InlineTextBox* next_text_box,
                                        size_t subrun_end);
 
+  void HandleTextNodeInNGBlockFlow(const LayoutNGBlockFlow&);
+
   // Used when the visibility of the style should not affect text gathering.
   bool IgnoresStyleVisibility() const {
     return behavior_.IgnoresStyleVisibility();
@@ -76,6 +81,15 @@ class TextIteratorTextNodeHandler final
   int offset_ = 0;
   int end_offset_ = 0;
 
+  // The current containing block if the text node is laid out with LayoutNG.
+  const LayoutNGBlockFlow* ng_block_flow_ = nullptr;
+
+  // The DOM to text content offset mapping in the containing block if the text
+  // node is laid out with LayoutNG.
+  // TODO(xiaochengh): The offset mapping should be managed in its own cached,
+  // not directly by its clients.
+  NGOffsetMappingResult mapping_result_;
+
   InlineTextBox* text_box_ = nullptr;
 
   // Remember if we are in the middle of handling a pre-formatted text node.