Consolidate RenderText adjacent word selection model code.

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 c4d48fd79058f9e81fb51816ea923052d7a02165..4999bc48dd35b95ab8ddc995bbd7d22d67eb85d6 100644
--- a/ui/gfx/render_text.h
+++ b/ui/gfx/render_text.h
@@ -367,9 +367,8 @@ class UI_EXPORT RenderText {
 
   // Get the selection model visually left/right of |selection| by one word.
   // The returned value represents a cursor/caret position without a selection.
-  virtual SelectionModel AdjacentWordSelectionModel(
-      const SelectionModel& selection,
-      VisualCursorDirection direction) = 0;
+  SelectionModel AdjacentWordSelectionModel(const SelectionModel& selection,
+                                            VisualCursorDirection direction);
 
   // Get the SelectionModels corresponding to visual text ends.
   // The returned value represents a cursor/caret position without a selection.