Add strings and notifier ID for low disk.

ash/common/system/system_notifier.cc

 // Copyright 2013 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 "ash/common/system/system_notifier.h"
 
 #include "base/logging.h"
 
 #if defined(OS_CHROMEOS)
 #include "ui/chromeos/network/network_state_notifier.h"
@@ skipping 21 matching lines @@
     kNotifierPower,
     // Note: Order doesn't matter here, so keep this in alphabetic order, don't
     // just add your stuff at the end!
     NULL};
 
 // |kAshSystemNotifiers| is the list of normal system notification sources for
 // ash events. These notifications can be hidden in some context.
 const char* kAshSystemNotifiers[] = {
   kNotifierBluetooth,
   kNotifierDisplayResolutionChange,
+#if defined(OS_CHROMEOS)
+  kNotifierDisk,
+#endif
   kNotifierLocale,
   kNotifierMultiProfileFirstRun,
 #if defined(OS_CHROMEOS)
   ui::NetworkStateNotifier::kNotifierNetwork,
 #endif
   kNotifierNetworkPortalDetector,
   kNotifierScreenshot,
   kNotifierScreenCapture,
   kNotifierScreenShare,
   kNotifierSessionLengthTimeout,
@@ skipping 14 matching lines @@
       return true;
   }
   return false;
 }
 
 }  // namespace
 
 const char kNotifierBattery[] = "ash.battery";
 const char kNotifierBluetooth[] = "ash.bluetooth";
 const char kNotifierDeprecatedAccelerator[] = "ash.accelerator-controller";
+const char kNotifierDisk[] = "ash.disk";
 const char kNotifierDisplay[] = "ash.display";
 const char kNotifierDisplayError[] = "ash.display.error";
 const char kNotifierDisplayResolutionChange[] = "ash.display.resolution-change";
 const char kNotifierDualRole[] = "ash.dual-role";
 const char kNotifierHats[] = "ash.hats";
 const char kNotifierLocale[] = "ash.locale";
 const char kNotifierMultiProfileFirstRun[] = "ash.multi-profile.first-run";
 const char kNotifierNetworkPortalDetector[] = "ash.network.portal-detector";
 const char kNotifierPower[] = "ash.power";
 const char kNotifierScreenshot[] = "ash.screenshot";
 const char kNotifierScreenCapture[] = "ash.screen-capture";
 const char kNotifierScreenShare[] = "ash.screen-share";
 const char kNotifierSessionLengthTimeout[] = "ash.session-length-timeout";
 const char kNotifierSupervisedUser[] = "ash.locally-managed-user";
 const char kNotifierWebUsb[] = "ash.webusb";
 
 bool ShouldAlwaysShowPopups(const message_center::NotifierId& notifier_id) {
   return MatchSystemNotifierId(notifier_id, kAlwaysShownSystemNotifierIds);
 }
 
 bool IsAshSystemNotifier(const message_center::NotifierId& notifier_id) {
   return ShouldAlwaysShowPopups(notifier_id) ||
          MatchSystemNotifierId(notifier_id, kAshSystemNotifiers);
 }
 
 }  // namespace system_notifier
 }  // namespace ash