Create ash memory monitor

ash/system/tray/system_tray.cc

Index: ash/system/tray/system_tray.cc
diff --git a/ash/system/tray/system_tray.cc b/ash/system/tray/system_tray.cc
index e3a0e252ec4da23881170750b752095dd05d9249..3cfca394a585b7e82d8cce17f43e0953ac5a5ac4 100644
--- a/ash/system/tray/system_tray.cc
+++ b/ash/system/tray/system_tray.cc
@@ -4,6 +4,7 @@
 
 #include "ash/system/tray/system_tray.h"
 
+#include "ash/ash_switches.h"
 #include "ash/shell.h"
 #include "ash/shell/panel_window.h"
 #include "ash/shell_window_ids.h"
@@ -15,6 +16,7 @@
 #include "ash/system/drive/tray_drive.h"
 #include "ash/system/ime/tray_ime.h"
 #include "ash/system/locale/tray_locale.h"
+#include "ash/system/monitor/tray_monitor.h"
 #include "ash/system/power/power_status_observer.h"
 #include "ash/system/power/power_supply_status.h"
 #include "ash/system/power/tray_power.h"
@@ -30,6 +32,7 @@
 #include "ash/system/user/login_status.h"
 #include "ash/system/user/tray_user.h"
 #include "ash/wm/shelf_layout_manager.h"
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/timer.h"
 #include "base/utf_string_conversions.h"
@@ -196,6 +199,14 @@ void SystemTray::CreateItems() {
   AddTrayItem(tray_caps_lock);
   AddTrayItem(tray_settings);
   AddTrayItem(tray_date);
+
+#if defined(OS_LINUX)
+  // Add memory monitor if enabled.
+  CommandLine* cmd = CommandLine::ForCurrentProcess();
+  if (cmd->HasSwitch(ash::switches::kAshEnableMemoryMonitor))
+    AddTrayItem(new internal::TrayMonitor);
+#endif
+
   SetVisible(ash::Shell::GetInstance()->tray_delegate()->
       GetTrayVisibilityOnStartup());
 }