[fsp] Let extensions decide about the file system id.

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

Index: chrome/browser/chromeos/extensions/file_manager/private_api_mount.cc
diff --git a/chrome/browser/chromeos/extensions/file_manager/private_api_mount.cc b/chrome/browser/chromeos/extensions/file_manager/private_api_mount.cc
index e30dd19b6fd6bdcc9a7c8b04a4611f9b54b10457..0c97f840ec9a3160404032fcfc1e0d14597c3253 100644
--- a/chrome/browser/chromeos/extensions/file_manager/private_api_mount.cc
+++ b/chrome/browser/chromeos/extensions/file_manager/private_api_mount.cc
@@ -130,8 +130,10 @@ bool FileBrowserPrivateRemoveMountFunction::RunAsync() {
           chromeos::file_system_provider::Service::Get(GetProfile());
       DCHECK(service);
       // TODO(mtomasz): Pass a more detailed error than just a bool.
-      if (!service->RequestUnmount(volume_info.file_system_id))
+      if (!service->RequestUnmount(volume_info.extension_id,
+                                   volume_info.file_system_id)) {
         return false;
+      }
       break;
     }
     default: