Instrument some of the exit paths likely to suffer hangs.

chrome/browser/ui/browser.cc

 // Copyright 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/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // defined(OS_WIN)
@@ skipping 183 matching lines @@
 #include "ui/base/window_open_disposition.h"
 #include "ui/gfx/point.h"
 #include "ui/shell_dialogs/selected_file_info.h"
 
 #if defined(OS_WIN)
 #include "base/win/metro.h"
 #include "chrome/browser/ssl/ssl_error_info.h"
 #include "chrome/browser/task_manager/task_manager.h"
 #include "chrome/browser/ui/view_ids.h"
 #include "components/autofill/core/browser/autofill_ie_toolbar_import_win.h"
+#include "components/browser_watcher/exit_funnel.h"
 #include "ui/base/touch/touch_device.h"
 #include "ui/base/win/shell.h"
 #endif  // OS_WIN
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/fileapi/external_file_url_util.h"
 #endif
 
 #if defined(USE_ASH)
 #include "ash/ash_switches.h"
@@ skipping 437 matching lines @@
   if (!ShouldCloseWindow())
     return;
 
   // Application should shutdown on last window close if the user is explicitly
   // trying to quit, or if there is nothing keeping the browser alive (such as
   // AppController on the Mac, or BackgroundContentsService for background
   // pages).
   bool should_quit_if_last_browser =
       browser_shutdown::IsTryingToQuit() || !chrome::WillKeepAlive();
 
   if (should_quit_if_last_browser && chrome::ShouldStartShutdown(this))

[sky, 2014/12/11 23:36:22]

you need to add {} here.

[Sigurður Ásgeirsson, 2014/12/12 20:09:23]

Phew - thanks. One thing I hadn't done yet is run any of this code :/

+#if defined(OS_WIN)
+    browser_watcher::ExitFunnel::RecordSingleEvent(
+          chrome::kBrowserExitCodesRegistryPath, L"LastWindowClose");
+#endif
     browser_shutdown::OnShutdownStarting(browser_shutdown::WINDOW_CLOSE);
 
   // Don't use GetForProfileIfExisting here, we want to force creation of the
   // session service so that user can restore what was open.
   SessionService* session_service =
       SessionServiceFactory::GetForProfile(profile());
   if (session_service)
     session_service->WindowClosing(session_id());
 
   TabRestoreService* tab_restore_service =
@@ skipping 1854 matching lines @@
   if (contents && !allow_js_access) {
     contents->web_contents()->GetController().LoadURL(
         target_url,
         content::Referrer(),
         ui::PAGE_TRANSITION_LINK,
         std::string());  // No extra headers.
   }
 
   return contents != NULL;
 }