Collects stats on how user interacts with the bubble.

ui/views/bubble/bubble_frame_view.cc

 // Copyright (c) 2012 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_frame_view.h"
 
 #include <algorithm>
 
+#include "base/bind.h"
 #include "grit/ui_resources.h"
 #include "ui/base/hit_test.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/path.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/views/bubble/bubble_border.h"
 #include "ui/views/controls/button/label_button.h"
 #include "ui/views/widget/widget.h"
@@ skipping 24 matching lines @@
   //  |      +------------------+       |
   //  |            bottom               |
   //  +---------------------------------+
   if (vertical)
     return std::max(0, available_bounds.y() - window_bounds.y()) +
            std::max(0, window_bounds.bottom() - available_bounds.bottom());
   return std::max(0, available_bounds.x() - window_bounds.x()) +
          std::max(0, window_bounds.right() - available_bounds.right());
 }
 
+// The default value for callback_before_close_.
+void EmptyCallback() {}
+
 }  // namespace
 
 namespace views {
 
 // static
 const char BubbleFrameView::kViewClassName[] = "BubbleFrameView";
 
 // static
 gfx::Insets BubbleFrameView::GetTitleInsets() {
   return gfx::Insets(kTitleTopInset, kTitleLeftInset,
                      kTitleBottomInset, kTitleRightInset);
 }
 
 BubbleFrameView::BubbleFrameView(const gfx::Insets& content_margins)
     : bubble_border_(NULL),
       content_margins_(content_margins),
       title_(NULL),
       close_(NULL),
-      titlebar_extra_view_(NULL) {
+      titlebar_extra_view_(NULL),
+      callback_before_close_(base::Bind(&EmptyCallback)) {

[Alexei Svitkine (slow), 2014/07/02 15:07:26]

I think you can initialize it with the default ctor and then just do:

if (!callback_before_close_.is_null())
  callback_before_close_.Run();

[yao, 2014/07/07 17:47:45]

Done.

   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   title_ = new Label(base::string16(),
                      rb.GetFontList(ui::ResourceBundle::MediumFont));
   title_->SetHorizontalAlignment(gfx::ALIGN_LEFT);
   AddChildView(title_);
 
   close_ = new LabelButton(this, base::string16());
   close_->SetImage(CustomButton::STATE_NORMAL,
                    *rb.GetImageNamed(IDR_CLOSE_DIALOG).ToImageSkia());
   close_->SetImage(CustomButton::STATE_HOVERED,
@@ skipping 149 matching lines @@
 
 void BubbleFrameView::OnNativeThemeChanged(const ui::NativeTheme* theme) {
   if (bubble_border_ && bubble_border_->use_theme_background_color()) {
     bubble_border_->set_background_color(GetNativeTheme()->
         GetSystemColor(ui::NativeTheme::kColorId_DialogBackground));
     SchedulePaint();
   }
 }
 
 void BubbleFrameView::ButtonPressed(Button* sender, const ui::Event& event) {
-  if (sender == close_)
+  if (sender == close_) {
+    callback_before_close_.Run();
     GetWidget()->Close();
+  }
 }
 
 void BubbleFrameView::SetBubbleBorder(scoped_ptr<BubbleBorder> border) {
   bubble_border_ = border.get();
   SetBorder(border.PassAs<Border>());
 
   // Update the background, which relies on the border.
   set_background(new views::BubbleBackground(bubble_border_));
 }
 
@@ skipping 108 matching lines @@
   if (titlebar_extra_view_ != NULL)
     title_bar_width += titlebar_extra_view_->GetPreferredSize().width();
   gfx::Size size(client_size);
   size.SetToMax(gfx::Size(title_bar_width, 0));
   const gfx::Insets insets(GetInsets());
   size.Enlarge(insets.width(), insets.height());
   return size;
 }
 
 }  // namespace views