[Sync] Fix namespaces for the sync_sessions component.

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index 29576617a77ded4e7f960be13bc5f1d07fdd2cea..ce09fda555d51df52fd7486f7ba63b0cde7d1be4 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -3372,6 +3372,7 @@ test("unit_tests") {
     "//components/sync:test_support_sync_api",
     "//components/sync:test_support_sync_core",
     "//components/sync:test_support_sync_core_impl",
+    "//components/sync_sessions:test_support",
     "//content/public/app:both",
     "//content/test:test_support",
     "//crypto:platform",
@@ -4921,8 +4922,6 @@ if (!is_android && !is_ios && !is_chromecast) {
 static_library("test_support_unit") {
   testonly = true
   sources = [
-    "../browser/sync/glue/session_sync_test_helper.cc",
-    "../browser/sync/glue/session_sync_test_helper.h",
     "base/run_all_unittests.cc",
   ]