MD Downloads: add first meaningful paint metrics to UMA

chrome/browser/ui/webui/md_downloads/md_downloads_ui.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 "chrome/browser/ui/webui/md_downloads/md_downloads_ui.h"
 
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/singleton.h"
 #include "base/strings/string_piece.h"
 #include "base/threading/thread.h"
 #include "base/values.h"
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/download/download_service.h"
 #include "chrome/browser/download/download_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.h"
+#include "chrome/browser/ui/webui/metrics_handler.h"
 #include "chrome/browser/ui/webui/theme_source.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/features.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/browser_resources.h"
 #include "chrome/grit/chromium_strings.h"
 #include "chrome/grit/generated_resources.h"
 #include "chrome/grit/theme_resources.h"
 #include "components/prefs/pref_service.h"
@@ skipping 110 matching lines @@
 // MdDownloadsUI
 //
 ///////////////////////////////////////////////////////////////////////////////
 
 MdDownloadsUI::MdDownloadsUI(content::WebUI* web_ui) : WebUIController(web_ui) {
   Profile* profile = Profile::FromWebUI(web_ui);
   DownloadManager* dlm = BrowserContext::GetDownloadManager(profile);
 
   handler_ = new MdDownloadsDOMHandler(dlm, web_ui);
   web_ui->AddMessageHandler(handler_);
+  web_ui->AddMessageHandler(new MetricsHandler);
 
   // Set up the chrome://downloads/ source.
   content::WebUIDataSource* source = CreateDownloadsUIHTMLSource(profile);
   content::WebUIDataSource::Add(profile, source);
   ThemeSource* theme = new ThemeSource(profile);
   content::URLDataSource::Add(profile, theme);
 }
 
 // static
 base::RefCountedMemory* MdDownloadsUI::GetFaviconResourceBytes(
     ui::ScaleFactor scale_factor) {
   return ResourceBundle::GetSharedInstance().
       LoadDataResourceBytesForScale(IDR_DOWNLOADS_FAVICON, scale_factor);
 }