Log the creation of dialog boxes using DialogDelegateView and BubbleDialogDelegateView.

ui/views/bubble/bubble_dialog_delegate.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #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"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/views/bubble/bubble_frame_view.h"
 #include "ui/views/focus/view_storage.h"
@@ skipping 197 matching lines @@
       color_explicitly_set_(false),
       accept_events_(true),
       adjust_if_offscreen_(true),
       parent_window_(NULL) {
   LayoutProvider* provider = LayoutProvider::Get();
   margins_ = provider->GetInsetsMetric(INSETS_BUBBLE_CONTENTS);
   title_margins_ = provider->GetInsetsMetric(INSETS_BUBBLE_TITLE);
   if (anchor_view)
     SetAnchorView(anchor_view);
   UpdateColorsFromTheme(GetNativeTheme());
+  UMA_HISTOGRAM_BOOLEAN("Dialog.BubbleDialogDelegateView.Creation", true);
 }
 
 gfx::Rect BubbleDialogDelegateView::GetBubbleBounds() {
   // The argument rect has its origin at the bubble's arrow anchor point;
   // its size is the preferred size of the bubble's client view (this view).
   bool anchor_minimized = anchor_widget() && anchor_widget()->IsMinimized();
   return GetBubbleFrameView()->GetUpdatedWindowBounds(
       GetAnchorRect(), GetWidget()->client_view()->GetPreferredSize(),
       adjust_if_offscreen_ && !anchor_minimized);
 }
@@ skipping 86 matching lines @@
   // http://crbug.com/474622 for details.
   if (widget == GetWidget() && visible) {
     ui::AXNodeData node_data;
     GetAccessibleNodeData(&node_data);
     if (node_data.role == ui::AX_ROLE_ALERT_DIALOG)
       NotifyAccessibilityEvent(ui::AX_EVENT_ALERT, true);
   }
 }
 
 }  // namespace views