[MarkersIntersectingRange #2.05] Add DocumentMarkerList::FirstMarkerIntersectingRange()

third_party/WebKit/Source/core/editing/markers/DocumentMarkerListEditor.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DocumentMarkerListEditor_h
 #define DocumentMarkerListEditor_h
 
 #include "core/editing/markers/DocumentMarkerList.h"
 #include "platform/heap/Handle.h"
 
@@ skipping 28 matching lines @@
                                            unsigned offset,
                                            unsigned old_length,
                                            unsigned new_length);
 
   // Returns true if a marker was shifted or removed, false otherwise.
   static bool ShiftMarkersContentIndependent(MarkerList*,
                                              unsigned offset,
                                              unsigned old_length,
                                              unsigned new_length);
 
+  // Returns the first marker in the specified MarkerList that has non-empty

[Xiaocheng, 2017/07/20 21:29:49]

Let's say "Returns the first marker whose interior overlaps with the range" so
that we don't get into troubles when the range is collapsed.

+  // overlap with the range [start_offset, end_offset], or null if there is no
+  // such marker.
+  static DocumentMarker* FirstMarkerIntersectingRange(const MarkerList&,
+                                                      unsigned start_offset,
+                                                      unsigned end_offset);
+
   static HeapVector<Member<DocumentMarker>> MarkersIntersectingRange(
       const MarkerList&,
       unsigned start_offset,
       unsigned end_offset);
 };
 
 }  // namespace blink
 
 #endif  // DocumentMarkerListEditor_h