Introduce Find{Left,Right}BoundaryOfBidiRun() and variations

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

Index: third_party/WebKit/Source/core/editing/InlineBoxTraversal.h
diff --git a/third_party/WebKit/Source/core/editing/InlineBoxTraversal.h b/third_party/WebKit/Source/core/editing/InlineBoxTraversal.h
new file mode 100644
index 0000000000000000000000000000000000000000..92bac5314b0c8e29d87f0497e14e92804c214c65
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/InlineBoxTraversal.h
@@ -0,0 +1,35 @@
+// 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);
+
+  // Find left boundary variations
+  static InlineBox* FindLeftBoundaryOfBidiRunIgnoringLineBreak(
+      const InlineBox&);
+  static InlineBox* FindLeftBoundaryOfEntireBidiRun(const InlineBox&);
+  static InlineBox* FindLeftBoundaryOfEntireBidiRunIgnoringLineBreak(
+      const InlineBox&);
+
+  // Find right boundary variations
+  static InlineBox* FindRightBoundaryOfBidiRunIgnoringLineBreak(
+      const InlineBox&);
+  static InlineBox* FindRightBoundaryOfEntireBidiRun(const InlineBox&);
+  static InlineBox* FindRightBoundaryOfEntireBidiRunIgnoringLineBreak(
+      const InlineBox&);
+};
+
+}  // namespace blink
+
+#endif  // InlineBoxTraversal_h