Log the creation of dialog boxes using DialogDelegateView and BubbleDialogDelegateView.

ui/views/window/dialog_delegate.cc

Index: ui/views/window/dialog_delegate.cc
diff --git a/ui/views/window/dialog_delegate.cc b/ui/views/window/dialog_delegate.cc
index 6af25ee59accfbcb26ef5379fe67751d4fff6cef..8dfd5144cc097e70a47eed768a1e8cbf330860ac 100644
--- a/ui/views/window/dialog_delegate.cc
+++ b/ui/views/window/dialog_delegate.cc
@@ -239,6 +239,7 @@ ui::AXRole DialogDelegate::GetAccessibleWindowRole() const {
 DialogDelegateView::DialogDelegateView() {
   // A WidgetDelegate should be deleted on DeleteDelegate.
   set_owned_by_client();
+  UMA_HISTOGRAM_BOOLEAN("Dialog.DelegateView.Create", true);

[msw, 2017/05/11 00:54:40]

nit: maybe this should be Dialog.DialogDelegateView.Create?

[pdyson, 2017/05/11 05:54:01]

Done.

I have another cl to change Dialog.Delegate.Creation to be of the form
Dialog.*.Create. So I'll make that Dialog.DialogDelegate.Create so this is all
consistent.

 }
 
 DialogDelegateView::~DialogDelegateView() {}