Lacros: Don't create status icons.

There is no system tray on ChromeOS so it does not make sense to create
status icons.

Bug: 1128963
Change-Id: I1a14371bd5a9d8c5e70ea72179308681917a1fcc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2528126
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825567}

chrome/browser/background/background_mode_manager.cc

@@ -25,6 +25,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
+#include "build/chromeos_buildflags.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/apps/app_service/app_service_proxy.h"
 #include "chrome/browser/apps/app_service/app_service_proxy_factory.h"
@@ -867,7 +868,7 @@ void BackgroundModeManager::CreateStatusTrayIcon() {
 
   // Since there are multiple profiles which share the status tray, we now
   // use the browser process to keep track of it.
-#if !defined(OS_MAC) && !defined(OS_CHROMEOS)
+#if !defined(OS_MAC) && !defined(OS_CHROMEOS) && !BUILDFLAG(IS_LACROS)
   if (!status_tray_)
     status_tray_ = g_browser_process->status_tray();
 #endif