Introduce Find{Left,Right}BidiRun() and utilize in AdjustInlineBoxPositionForTextDirection()

third_party/WebKit/Source/core/editing/InlineBoxTraversal.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 InlineBoxTraversal_h
 #define InlineBoxTraversal_h
 
 #include "platform/wtf/Allocator.h"
 
 namespace blink {
 
 class InlineBox;
 
 // This class provides common traveral functions on list of |InlineBox|.
 class InlineBoxTraversal final {
   STATIC_ONLY(InlineBoxTraversal);
 
  public:
   // TODO(yosin): We should take |bidi_level| from |InlineBox::BidiLevel()|,
   // once all call sites satisfy it.
+
+  // Returns |InlineBox| which is less than or equal to |bidi_level| of
+  // left/right of specified |InlineBox|.
+  static InlineBox* FindLeftBidiRun(const InlineBox&, unsigned bidi_level);
+  static InlineBox* FindRightBidiRun(const InlineBox&, unsigned bidi_level);
+
   // Find left boundary variations
   static InlineBox* FindLeftBoundaryOfBidiRunIgnoringLineBreak(
       const InlineBox&,
       unsigned bidi_level);
   static InlineBox* FindLeftBoundaryOfEntireBidiRun(const InlineBox&,
                                                     unsigned bidi_level);
   static InlineBox* FindLeftBoundaryOfEntireBidiRunIgnoringLineBreak(
       const InlineBox&,
       unsigned bidi_level);
 
   // Find right boundary variations
   static InlineBox* FindRightBoundaryOfBidiRunIgnoringLineBreak(
       const InlineBox&,
       unsigned bidi_level);
   static InlineBox* FindRightBoundaryOfEntireBidiRun(const InlineBox&,
                                                      unsigned bidi_level);
   static InlineBox* FindRightBoundaryOfEntireBidiRunIgnoringLineBreak(
       const InlineBox&,
       unsigned bidi_level);
 };
 
 }  // namespace blink
 
 #endif  // InlineBoxTraversal_h