Make mouse drag to ignore unfocused selection

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  * Copyright (C) 2015 Google 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:
@@ skipping 335 matching lines @@
 
   Node* target = hit_test_result.InnerNode();
   if (!target)
     return;
 
   // TODO(editing-dev): Use of updateStyleAndLayoutIgnorePendingStylesheets
   // needs to be audited.  See http://crbug.com/590369 for more details.
   frame_->GetDocument()->UpdateStyleAndLayoutIgnorePendingStylesheets();
 
   const PositionWithAffinity& raw_target_position =
-      PositionRespectingEditingBoundary(
-          Selection().ComputeVisibleSelectionInDOMTree().Start(),
-          hit_test_result.LocalPoint(), target);
+      Selection().SelectionHasFocus()
+          ? PositionRespectingEditingBoundary(
+                Selection().ComputeVisibleSelectionInDOMTree().Start(),
+                hit_test_result.LocalPoint(), target)
+          : PositionWithAffinity();
   VisiblePositionInFlatTree target_position = CreateVisiblePosition(
       FromPositionInDOMTree<EditingInFlatTreeStrategy>(raw_target_position));
   // Don't modify the selection if we're not on a node.
   if (target_position.IsNull())
     return;
 
   // Restart the selection if this is the first mouse move. This work is usually
   // done in handleMousePressEvent, but not if the mouse press was on an
   // existing selection.
 
@@ skipping 762 matching lines @@
 
 bool IsExtendingSelection(const MouseEventWithHitTestResults& event) {
   bool is_mouse_down_on_link_or_image =
       event.IsOverLink() || event.GetHitTestResult().GetImage();
   return (event.Event().GetModifiers() & WebInputEvent::Modifiers::kShiftKey) !=
              0 &&
          !is_mouse_down_on_link_or_image;
 }
 
 }  // namespace blink