Support PolicyWatcher with custom loader for testing

remoting/host/policy_watcher.cc

Index: remoting/host/policy_watcher.cc
diff --git a/remoting/host/policy_watcher.cc b/remoting/host/policy_watcher.cc
index b21da1bac6a43659e31ebaa26eb0564c17c72f15..569e3289c887f130aa6dcbf0dc79105f2a27f629 100644
--- a/remoting/host/policy_watcher.cc
+++ b/remoting/host/policy_watcher.cc
@@ -390,4 +390,9 @@ std::unique_ptr<PolicyWatcher> PolicyWatcher::Create(
 #endif  // !(OS_CHROMEOS)
 }
 
+std::unique_ptr<PolicyWatcher> PolicyWatcher::CreateFromPolicyLoaderForTesting(
+    std::unique_ptr<policy::AsyncPolicyLoader> async_policy_loader) {
+  return CreateFromPolicyLoader(std::move(async_policy_loader));
+}
+
 }  // namespace remoting