Introduce IsGraphemeBreak function.

third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.h

Index: third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.h
diff --git a/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.h b/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.h
new file mode 100644
index 0000000000000000000000000000000000000000..39e5893f40955212ad9bd10ba756162b546abaee
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.h
@@ -0,0 +1,22 @@
+// Copyright 2016 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 StateMachineUtil_h
+#define StateMachineUtil_h
+
+#include "core/CoreExport.h"
+#include "wtf/text/Unicode.h"
+
+namespace blink {
+
+// Returns true if there is a grapheme boundary between prevCodePoint and
+// nextCodePoint.
+// DO NOT USE this function directly since this doesn't care about preceding
+// regional indicator symbols. Use ForwardGraphemeBoundaryStateMachine or
+// BackwardGraphemeBoundaryStateMachine instead.
+CORE_EXPORT bool isGraphemeBreak(UChar32 prevCodePoint, UChar32 nextCodePoint);
+
+} // namespace blink
+
+#endif // StateMachineUtil_h