Do not send redundant selectionchange-events (decouple focus)

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

Index: third_party/WebKit/Source/core/editing/EditingUtilities.cpp
diff --git a/third_party/WebKit/Source/core/editing/EditingUtilities.cpp b/third_party/WebKit/Source/core/editing/EditingUtilities.cpp
index 736d889bf286020e88b7afa6ef2f399bf276d8fd..488d718b20351078c9bf732a3a7c27a4e4b3ac36 100644
--- a/third_party/WebKit/Source/core/editing/EditingUtilities.cpp
+++ b/third_party/WebKit/Source/core/editing/EditingUtilities.cpp
@@ -374,6 +374,23 @@ Element* rootEditableElement(const Node& node) {
   return toElement(const_cast<Node*>(result));
 }
 
+bool selectionHasFocus(const SelectionInFlatTree& selection) {
+  const Document* document = selection.base().document();

[yosin_UTC9, 2017/03/22 09:11:35]

Let's handle document == nullptr case, selection.isNone(), for ease of using
this function.

[hugoh_UTC2, 2017/03/22 09:19:14]

You mean when selection.isNone(), we return false? 

!selection.isNone() => document != nullptr ?

[yosin_UTC9, 2017/03/22 09:26:35]

Yes, just return false if selection.isNone(),

So, we can write

if (!document)
  return false;

Since there is no selection, it can not have focus.

[hugoh_UTC2, 2017/03/22 09:41:11]

Done. See PS26.

+  const Element* focus = document->focusedElement();
+  if (!focus) {
+    // No focused element means document root has focus.
+    focus = document->documentElement();
+  }
+
+  const Node* const nodeWhereSelectionStarts =
+      selection.base().computeContainerNode();
+  const Node* const nodeWhereSelectionEnds =
+      selection.extent().computeContainerNode();
+
+  return focus->containsIncludingHostElements(*nodeWhereSelectionStarts) ||
+         focus->containsIncludingHostElements(*nodeWhereSelectionEnds);
+}
+
 ContainerNode* highestEditableRoot(
     const Position& position,
     Element* (*rootEditableElementOf)(const Position&),