Reland: Fix setComposingText with empty text when newCursorPosition != 1

content/renderer/render_widget.h

 // Copyright (c) 2012 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 CONTENT_RENDERER_RENDER_WIDGET_H_
 #define CONTENT_RENDERER_RENDER_WIDGET_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 763 matching lines @@
   // Wraps the |webwidget_| as a MouseLockDispatcher::LockTarget interface.
   std::unique_ptr<MouseLockDispatcher::LockTarget> webwidget_mouse_lock_target_;
 
  private:
   // When emulated, this returns original device scale factor.
   float GetOriginalDeviceScaleFactor() const;
 
   // Indicates whether this widget has focus.
   bool has_focus_;
 
+  // When selection exceeds the boundary, it should stay at the boundary.
+  void adjustSelectionForBoundary(int& selectionStart,
+                                  int& selectionEnd,
+                                  const int textLength) const;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_WIDGET_H_