Add new UMA stats to get a handle on Downloads UI Usage

chrome/browser/ui/cocoa/download/download_shelf_controller.mm

 // Copyright (c) 2011 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.
 
 #import "chrome/browser/ui/cocoa/download/download_shelf_controller.h"
 
 #include "base/mac/mac_util.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/ui/browser.h"
 #import "chrome/browser/ui/cocoa/animatable_view.h"
 #include "chrome/browser/ui/cocoa/browser_window_cocoa.h"
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 #include "chrome/browser/ui/cocoa/download/download_item_controller.h"
 #include "chrome/browser/ui/cocoa/download/download_shelf_mac.h"
 #import "chrome/browser/ui/cocoa/download/download_shelf_view.h"
 #import "chrome/browser/ui/cocoa/hover_button.h"
 #import "chrome/browser/ui/cocoa/presentation_mode_controller.h"
 #include "content/browser/download/download_item.h"
 #include "content/browser/download/download_manager.h"
+#include "content/browser/download/download_stats.h"
 #import "third_party/GTM/AppKit/GTMNSAnimation+Duration.h"
 #include "ui/base/l10n/l10n_util.h"
 
 // Download shelf autoclose behavior:
 //
 // The download shelf autocloses if all of this is true:
 // 1) An item on the shelf has just been opened.
 // 2) All remaining items on the shelf have been opened in the past.
 // 3) The mouse leaves the shelf and remains off the shelf for 5 seconds.
 //
@@ skipping 200 matching lines @@
   return barIsVisible_;
 }
 
 - (void)show:(id)sender {
   [self showDownloadShelf:YES];
 }
 
 - (void)hide:(id)sender {
   [self cancelAutoCloseAndRemoveTrackingArea];
 
+  download_stats::RecordShelfSize([downloadItemControllers_ count]);
+
   // If |sender| isn't nil, then we're being closed from the UI by the user and
   // we need to tell our shelf implementation to close. Otherwise, we're being
   // closed programmatically by our shelf implementation.
   if (sender)
     bridge_->Close();
   else
     [self showDownloadShelf:NO];
 }
 
 - (void)animationDidEnd:(NSAnimation*)animation {
@@ skipping 186 matching lines @@
   }
 
   // Set the tracking off to create a new tracking area for the control.
   // When changing the bounds/frame on a HoverButton, the tracking isn't updated
   // correctly, it needs to be turned off and back on.
   [hoverCloseButton_ setTrackingEnabled:NO];
   [hoverCloseButton_ setFrame:bounds];
   [hoverCloseButton_ setTrackingEnabled:YES];
 }
 @end