MacViews/a11y: Allow accessibility clients to update the selected text.

ui/views/controls/textfield/textfield.h

Index: ui/views/controls/textfield/textfield.h
diff --git a/ui/views/controls/textfield/textfield.h b/ui/views/controls/textfield/textfield.h
index 5b21c054eef33157fb979cc6295ba72fe0f72fdc..af7a82828e2c034a010289ca65c9e8556922d076 100644
--- a/ui/views/controls/textfield/textfield.h
+++ b/ui/views/controls/textfield/textfield.h
@@ -331,6 +331,8 @@ class VIEWS_EXPORT Textfield : public View,
   // using an accessibility API (typically automation software, screen readers
   // don't normally use this). Sets the value and clears the selection.
   void AccessibilitySetValue(const base::string16& new_value);
+  // Same as above, but replaces selected text/inserts new text at the cursor.
+  void AccessibilityReplaceSelection(const base::string16& new_value);
 
   // Updates the painted background color.
   void UpdateBackgroundColor();