[MarkersIntersectingRange #2.1] Add DocumentMarkerController::FirstMarkerIntersectingOffsetRange()

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

Index: third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
diff --git a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
index 64d9ebdb2ac32b413c008162d48ba1d76fef6fc3..c8a4e4192ec35d8b66dc11b72bee6b40607f60dc 100644
--- a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
+++ b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
@@ -94,6 +94,17 @@ class CORE_EXPORT DocumentMarkerController final
   // Position in its interior (not at an endpoint), if one exists.
   DocumentMarker* MarkerAtPosition(const Position&,
                                    DocumentMarker::MarkerTypes);
+  // Looks for a marker in the specified node of the specified type whose
+  // interior has non-empty overlap with the range [start_offset, end_offset].
+  // If the range is collapsed, this looks for a marker containing the offset of
+  // the collapsed range in its interior.
+  // If such a marker exists, this method will return one of them (no guarantees
+  // are provided as to which one). Otherwise, this method will return null.
+  DocumentMarker* FirstMarkerIntersectingOffsetRange(
+      const Text&,
+      unsigned start_offset,
+      unsigned end_offset,
+      DocumentMarker::MarkerTypes);
   DocumentMarkerVector MarkersFor(
       Node*,
       DocumentMarker::MarkerTypes = DocumentMarker::AllMarkers());