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 5eb167deedcdbd5ddb0bbcf9fbbe939a8f3d65cb..72fcab4b933a7752a3a45f881fbf8e242abf53b3 100644
--- a/ui/views/controls/textfield/textfield.h
+++ b/ui/views/controls/textfield/textfield.h
@@ -365,8 +365,11 @@ class VIEWS_EXPORT Textfield : public View,
 
   // Handles a request to change the value of this text field from software
   // 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);
+  // don't normally use this). If |clear_first| is true, clears the existing
+  // value first and sets it to |new_value|. If false, deletes whatever's
+  // selected and replaces it with |new_value|. The cursor is then placed at the
+  // end of |new_value|.
+  void AccessibilitySetValue(const base::string16& new_value, bool clear_first);
 
   // Updates the painted background color.
   void UpdateBackgroundColor();