Do not send redundant selectionchange-events (decouple focus)

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

Index: third_party/WebKit/Source/core/editing/PendingSelection.cpp
diff --git a/third_party/WebKit/Source/core/editing/PendingSelection.cpp b/third_party/WebKit/Source/core/editing/PendingSelection.cpp
index 1b106656d49673990d8f12016ed2f04fad889264..1a52dcc68f36be1a3e7046923a281e6477df1a97 100644
--- a/third_party/WebKit/Source/core/editing/PendingSelection.cpp
+++ b/third_party/WebKit/Source/core/editing/PendingSelection.cpp
@@ -106,6 +106,27 @@ SelectionInFlatTree PendingSelection::calcVisibleSelection(
   return builder.build();
 }
 
+static bool selectionHasFocus(const LayoutView& layoutView,
+                              const VisibleSelectionInFlatTree& selection) {
+  if (!isSelectionInDocument(selection, layoutView.document()))
+    return false;
+
+  const LocalFrame* const frame = layoutView.document().frame();
+  const Element* focus = frame->document()->focusedElement();
+  if (!focus) {
+    // No focused element means document has focus.
+    focus = layoutView.document().documentElement();

[hugoh_UTC2, 2017/03/10 10:10:37]

I use document().documentElement(), not document.body() so non HTML-documents
(here SVG documents) also can have selected text.

+  }
+
+  const Node* const nodeWhereSelectionStarts =
+      selection.base().computeContainerNode();
+  const Node* const nodeWhereSelectionEnds =
+      selection.extent().computeContainerNode();
+
+  return focus->containsIncludingHostElements(*nodeWhereSelectionStarts) ||
+         focus->containsIncludingHostElements(*nodeWhereSelectionEnds);
+}
+
 void PendingSelection::commit(LayoutView& layoutView) {
   if (!hasPendingSelection())
     return;
@@ -126,7 +147,7 @@ void PendingSelection::commit(LayoutView& layoutView) {
   const VisibleSelectionInFlatTree& selection =
       createVisibleSelection(calcVisibleSelection(originalSelection));
 
-  if (!selection.isRange()) {
+  if (!selection.isRange() || !selectionHasFocus(layoutView, selection)) {
     layoutView.clearSelection();
     return;
   }