Add a method to remount all removable devices in DiskMountManager.

chrome/browser/chromeos/extensions/file_manager/device_event_router.cc

Index: chrome/browser/chromeos/extensions/file_manager/device_event_router.cc
diff --git a/chrome/browser/chromeos/extensions/file_manager/device_event_router.cc b/chrome/browser/chromeos/extensions/file_manager/device_event_router.cc
index b12bf26f9f9c7a40e919389ea8b4b1be37306521..a2e8168e17bac9e74a78398eda7a2c1c5b0362ad 100644
--- a/chrome/browser/chromeos/extensions/file_manager/device_event_router.cc
+++ b/chrome/browser/chromeos/extensions/file_manager/device_event_router.cc
@@ -78,7 +78,7 @@ void DeviceEventRouter::OnDiskRemoved(
     return;
 
   const std::string& device_path = disk.system_path_prefix();
-  if (!disk.is_read_only() && !disk.mount_path().empty() &&
+  if (!disk.is_read_only() && disk.is_mounted() &&
       GetDeviceState(device_path) != DEVICE_HARD_UNPLUGGED_AND_REPORTED) {
     OnDeviceEvent(file_manager_private::DEVICE_EVENT_TYPE_HARD_UNPLUGGED,
                   device_path);