[RenderText] Added append text

ui/gfx/render_text.h

Index: ui/gfx/render_text.h
diff --git a/ui/gfx/render_text.h b/ui/gfx/render_text.h
index 6170c57c28a88251cfa2c7214fe709995789ffb8..fe70f4761beed7b7117b96605d9803a41d8906e3 100644
--- a/ui/gfx/render_text.h
+++ b/ui/gfx/render_text.h
@@ -207,6 +207,7 @@ class GFX_EXPORT RenderText {
 
   const base::string16& text() const { return text_; }
   void SetText(const base::string16& text);
+  void AppendText(const base::string16& text);
 
   HorizontalAlignment horizontal_alignment() const {
     return horizontal_alignment_;
@@ -603,6 +604,9 @@ class GFX_EXPORT RenderText {
   size_t TextIndexToGivenTextIndex(const base::string16& given_text,
                                    size_t index);
 
+  // Adjust ranged styles to accommodate a new text length.
+  void UpdateStyleLengths();
+
   // A convenience function to check whether the glyph attached to the caret
   // is within the given range.
   static bool RangeContainsCaret(const Range& range,