Switch GlobalErrorBubbleView to a BubbleDialogDelegate.

ui/views/window/dialog_delegate.h

Index: ui/views/window/dialog_delegate.h
diff --git a/ui/views/window/dialog_delegate.h b/ui/views/window/dialog_delegate.h
index 87bf36a29d43215640b99723ee290c3ddb4706ee..ca83c29293b177c4a7ba03be72b798dfbc7de859 100644
--- a/ui/views/window/dialog_delegate.h
+++ b/ui/views/window/dialog_delegate.h
@@ -16,6 +16,7 @@
 namespace views {
 
 class DialogClientView;
+class LabelButton;
 
 ///////////////////////////////////////////////////////////////////////////////
 //
@@ -80,6 +81,11 @@ class VIEWS_EXPORT DialogDelegate : public ui::DialogModel,
   // window can be closed after it returns, or false if it must remain open.
   virtual bool Close();
 
+  // Updates the properties and appearance of |button| which has been created
+  // for type |type|. Override to do special initialization above and beyond
+  // the typical.
+  virtual void UpdateButton(LabelButton* button, ui::DialogButton type);
+
   // Overridden from ui::DialogModel:
   base::string16 GetDialogTitle() const override;
   int GetDialogButtons() const override;