Treat selection as focused if it contains focused element

third_party/WebKit/Source/core/editing/FrameSelection.cpp

 /*
  * Copyright (C) 2004, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 416 matching lines @@
 bool FrameSelection::SelectionHasFocus() const {
   // TODO(editing-dev): Hoist UpdateStyleAndLayoutIgnorePendingStylesheets
   // to caller. See http://crbug.com/590369 for more details.
   GetDocument().UpdateStyleAndLayoutIgnorePendingStylesheets();
   const Node* current =
       ComputeVisibleSelectionInDOMTree().Start().ComputeContainerNode();
   if (!current)
     return false;
 
   // No focused element means document root has focus.
-  const Element* const focused_element = GetDocument().FocusedElement()
-                                             ? GetDocument().FocusedElement()
-                                             : GetDocument().documentElement();
+  Element* const focused_element = GetDocument().FocusedElement()
+                                       ? GetDocument().FocusedElement()
+                                       : GetDocument().documentElement();
   if (!focused_element)
     return false;
 
   if (focused_element->IsTextControl())
     return focused_element->ContainsIncludingHostElements(*current);
 
+  // Selection has focus if it contains the focused element.
+  const PositionInFlatTree focused_position(focused_element, 0);

[yosin_UTC9, 2017/05/23 01:15:50]

It is better to use PositionInFlatTree::FirstPositionInNode(focused_element)?

Because, we want to deprecated Node/offset ctor:

  // For creating offset positions:
  // FIXME: This constructor should eventually go away. See bug 63040.
  PositionTemplate(Node* anchor_node, int offset);


https://bugs.webkit.org/show_bug.cgi?id=63040
[meta] positionIsOffsetInAnchor should only accept text nodes

+  if (ComputeVisibleSelectionInFlatTree().Start() <= focused_position &&
+      ComputeVisibleSelectionInFlatTree().end() >= focused_position)
+    return true;
+
   bool has_editable_style = HasEditableStyle(*current);
   do {
     // If the selection is within an editable sub tree and that sub tree
     // doesn't have focus, the selection doesn't have focus either.
     if (has_editable_style && !HasEditableStyle(*current))
       return false;
 
     // Selection has focus if its sub tree has focus.
     if (current == focused_element)
       return true;
@@ skipping 727 matching lines @@
 }
 
 void showTree(const blink::FrameSelection* sel) {
   if (sel)
     sel->ShowTreeForThis();
   else
     LOG(INFO) << "Cannot showTree for <null> FrameSelection.";
 }
 
 #endif