Added web::GetCommittedItemWithUniqueID function.

ios/web/BUILD.gn

Index: ios/web/BUILD.gn
diff --git a/ios/web/BUILD.gn b/ios/web/BUILD.gn
index ad24765a7c48e7d13e86c08ebdff7b01ae6c8dbe..b5e1ad881d76550652f51dace47d932187d08771 100644
--- a/ios/web/BUILD.gn
+++ b/ios/web/BUILD.gn
@@ -66,6 +66,8 @@ source_set("web_arc") {
     "navigation/navigation_manager_delegate.h",
     "navigation/navigation_manager_impl.h",
     "navigation/navigation_manager_impl.mm",
+    "navigation/navigation_manager_util.h",
+    "navigation/navigation_manager_util.mm",
     "navigation/nscoder_util.h",
     "navigation/nscoder_util.mm",
     "navigation/serializable_user_data_manager_impl.h",
@@ -538,6 +540,7 @@ test("ios_web_unittests_arc") {
   ]
 
   sources = [
+    "navigation/navigation_manager_util_unittest.mm",
     "public/crw_session_certificate_policy_cache_storage_unittest.mm",
     "web_state/session_certificate_policy_cache_impl_unittest.mm",
     "web_state/session_certificate_policy_cache_storage_builder_unittest.mm",