Log the creation of dialog boxes using DialogDelegateView and BubbleDialogDelegateView.

ui/views/bubble/bubble_dialog_delegate.cc

Index: ui/views/bubble/bubble_dialog_delegate.cc
diff --git a/ui/views/bubble/bubble_dialog_delegate.cc b/ui/views/bubble/bubble_dialog_delegate.cc
index 0f239090451351e9ed2b1b2358027eb24c4f6342..5759c8a8a12e0bb056fde2a2553da7571d4a5d3d 100644
--- a/ui/views/bubble/bubble_dialog_delegate.cc
+++ b/ui/views/bubble/bubble_dialog_delegate.cc
@@ -4,6 +4,7 @@
 
 #include "ui/views/bubble/bubble_dialog_delegate.h"
 
+#include "base/metrics/histogram_macros.h"
 #include "build/build_config.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/base/default_style.h"
@@ -221,6 +222,7 @@ BubbleDialogDelegateView::BubbleDialogDelegateView(View* anchor_view,
   if (anchor_view)
     SetAnchorView(anchor_view);
   UpdateColorsFromTheme(GetNativeTheme());
+  UMA_HISTOGRAM_BOOLEAN("Dialog.BubbleDialogDelegateView.Creation", true);
 }
 
 gfx::Rect BubbleDialogDelegateView::GetBubbleBounds() {