[LayoutNG] Add NGText class definition

third_party/WebKit/Source/core/layout/ng/NGText.h

 // 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 NGFragment_h
-#define NGFragment_h
+#ifndef NGText_h
+#define NGText_h
 
 #include "core/CoreExport.h"
 #include "platform/LayoutUnit.h"
+#include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class CORE_EXPORT NGFragment final {
+class CORE_EXPORT NGText final {
 public:
-    NGFragment(LayoutUnit inlineSize, LayoutUnit blockSize);
-    ~NGFragment() { }
+    NGText(LayoutUnit inlineSize, LayoutUnit blockSize);
+    ~NGText() { }
 
     LayoutUnit inlineSize() const { return m_inlineSize; }
     LayoutUnit blockSize() const { return m_blockSize; }
 
     LayoutUnit inlineOffset() const { return m_inlineOffset; }
     LayoutUnit blockOffset() const { return m_blockOffset; }
 
+    const String text() const { return String(); }
+
     void setOffset(LayoutUnit inlineOffset, LayoutUnit blockOffset);
 
 private:
     LayoutUnit m_inlineSize;
     LayoutUnit m_blockSize;
 
     LayoutUnit m_inlineOffset;
     LayoutUnit m_blockOffset;
 };
 
 } // namespace blink
 
-#endif // NGFragment_h
+#endif // NGText_h