Refactor ShadowBoundaryAdjuster.

This patch makes only-internal-used functions declared in header
to local.
This patch also moves internal functions from anonymous namespace
to ShadowBoundaryAdjuster.

Bug: 787295
Change-Id: I4420a2f7364cd41b8a6bf25aefbce79b7991c1f3
Reviewed-on: https://chromium-review.googlesource.com/803177Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521309}

third_party/WebKit/Source/core/editing/SelectionAdjuster.h

@@ -19,15 +19,6 @@ class CORE_EXPORT SelectionAdjuster final {
   STATIC_ONLY(SelectionAdjuster);
 
  public:
-  // TODO(editing-dev): Move these functions to ShadowBoundaryAdjuster.
-  static Position AdjustSelectionStartToAvoidCrossingShadowBoundaries(
-      const EphemeralRange&);
-  static Position AdjustSelectionEndToAvoidCrossingShadowBoundaries(
-      const EphemeralRange&);
-  static PositionInFlatTree AdjustSelectionStartToAvoidCrossingShadowBoundaries(
-      const EphemeralRangeInFlatTree&);
-  static PositionInFlatTree AdjustSelectionEndToAvoidCrossingShadowBoundaries(
-      const EphemeralRangeInFlatTree&);
   static SelectionInDOMTree AdjustSelectionRespectingGranularity(
       const SelectionInDOMTree&,
       TextGranularity);