Refactor PolicyWatcher to allow mocking

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..da7a16334128103bee2e236540bd4180bd1626e4 100644
--- a/remoting/host/policy_watcher.cc
+++ b/remoting/host/policy_watcher.cc
@@ -47,6 +47,70 @@ namespace key = ::policy::key;
 
 namespace {
 
+// Watches for changes to the managed remote access host policies.
+class PolicyWatcherImpl : public PolicyWatcher,
+                          private policy::PolicyService::Observer {
+ public:
+  // |policy_service_task_runner| is the task runner where it is safe
+  // to call |policy_service_| methods and where we expect to get callbacks
+  // from |policy_service_|.
+  PolicyWatcherImpl(
+      policy::PolicyService* policy_service,
+      std::unique_ptr<policy::PolicyService> owned_policy_service,
+      std::unique_ptr<policy::ConfigurationPolicyProvider>
+          owned_policy_provider,
+      std::unique_ptr<policy::SchemaRegistry> owned_schema_registry);
+
+  ~PolicyWatcherImpl() override;
+
+  void StartWatching(const PolicyUpdatedCallback& policy_updated_callback,
+                     const PolicyErrorCallback& policy_error_callback) override;
+
+ private:
+  friend class PolicyWatcherTest;
+
+  const policy::Schema* GetPolicySchema() const override;
+  const base::DictionaryValue* GetDefaultValues() const override;
+
+  // Simplifying wrapper around Schema::Normalize.
+  // - Returns false if |dict| is invalid (i.e. contains mistyped policy
+  // values).
+  // - Returns true if |dict| was valid or got normalized.
+  bool NormalizePolicies(base::DictionaryValue* dict);
+
+  // Stores |new_policies| into |old_policies_|.  Returns dictionary with items
+  // from |new_policies| that are different from the old |old_policies_|.
+  std::unique_ptr<base::DictionaryValue> StoreNewAndReturnChangedPolicies(
+      std::unique_ptr<base::DictionaryValue> new_policies);
+
+  // Signals policy error to the registered |PolicyErrorCallback|.
+  void SignalPolicyError();
+
+  // PolicyService::Observer interface.
+  void OnPolicyUpdated(const policy::PolicyNamespace& ns,
+                       const policy::PolicyMap& previous,
+                       const policy::PolicyMap& current) override;
+  void OnPolicyServiceInitialized(policy::PolicyDomain domain) override;
+
+  PolicyUpdatedCallback policy_updated_callback_;
+  PolicyErrorCallback policy_error_callback_;
+
+  std::unique_ptr<base::DictionaryValue> old_policies_;
+  std::unique_ptr<base::DictionaryValue> default_values_;
+
+  policy::PolicyService* policy_service_;
+
+  // Order of fields below is important to ensure destruction takes object
+  // dependencies into account:
+  // - |owned_policy_service_| uses |owned_policy_provider_|
+  // - |owned_policy_provider_| uses |owned_schema_registry_|
+  std::unique_ptr<policy::SchemaRegistry> owned_schema_registry_;
+  std::unique_ptr<policy::ConfigurationPolicyProvider> owned_policy_provider_;
+  std::unique_ptr<policy::PolicyService> owned_policy_service_;
+
+  DISALLOW_COPY_AND_ASSIGN(PolicyWatcherImpl);
+};
+
 // Copies all policy values from one dictionary to another, using values from
 // |default_values| if they are not set in |from|.
 std::unique_ptr<base::DictionaryValue> CopyValuesAndAddDefaults(
@@ -136,9 +200,16 @@ bool VerifyWellformedness(const base::DictionaryValue& changed_policies) {
   return true;
 }
 
-}  // namespace
+void CopyDictionaryValue(const base::DictionaryValue& from,
+                         base::DictionaryValue& to,
+                         std::string key) {
+  const base::Value* value;
+  if (from.Get(key, &value)) {
+    to.Set(key, value->CreateDeepCopy());
+  }
+}
 
-void PolicyWatcher::StartWatching(
+void PolicyWatcherImpl::StartWatching(
     const PolicyUpdatedCallback& policy_updated_callback,
     const PolicyErrorCallback& policy_error_callback) {
   DCHECK(CalledOnValidThread());
@@ -158,12 +229,12 @@ void PolicyWatcher::StartWatching(
   }
 }
 
-void PolicyWatcher::SignalPolicyError() {
+void PolicyWatcherImpl::SignalPolicyError() {
   old_policies_->Clear();
   policy_error_callback_.Run();
 }
 
-PolicyWatcher::PolicyWatcher(
+PolicyWatcherImpl::PolicyWatcherImpl(
     policy::PolicyService* policy_service,
     std::unique_ptr<policy::PolicyService> owned_policy_service,
     std::unique_ptr<policy::ConfigurationPolicyProvider> owned_policy_provider,
@@ -199,7 +270,7 @@ PolicyWatcher::PolicyWatcher(
       key::kRemoteAccessHostAllowUiAccessForRemoteAssistance, false);
 }
 
-PolicyWatcher::~PolicyWatcher() {
+PolicyWatcherImpl::~PolicyWatcherImpl() {
   // Stop observing |policy_service_| if StartWatching() has been called.
   if (!policy_updated_callback_.is_null()) {
     policy_service_->RemoveObserver(policy::POLICY_DOMAIN_CHROME, this);
@@ -210,11 +281,15 @@ PolicyWatcher::~PolicyWatcher() {
   }
 }
 
-const policy::Schema* PolicyWatcher::GetPolicySchema() const {
+const policy::Schema* PolicyWatcherImpl::GetPolicySchema() const {
   return owned_schema_registry_->schema_map()->GetSchema(GetPolicyNamespace());
 }
 
-bool PolicyWatcher::NormalizePolicies(base::DictionaryValue* policy_dict) {
+const base::DictionaryValue* PolicyWatcherImpl::GetDefaultValues() const {
+  return default_values_.get();
+}
+
+bool PolicyWatcherImpl::NormalizePolicies(base::DictionaryValue* policy_dict) {
   // Allowing unrecognized policy names allows presence of
   // 1) comments (i.e. JSON of the form: { "_comment": "blah", ... }),
   // 2) policies intended for future/newer versions of the host,
@@ -239,19 +314,8 @@ bool PolicyWatcher::NormalizePolicies(base::DictionaryValue* policy_dict) {
   }
 }
 
-namespace {
-void CopyDictionaryValue(const base::DictionaryValue& from,
-                         base::DictionaryValue& to,
-                         std::string key) {
-  const base::Value* value;
-  if (from.Get(key, &value)) {
-    to.Set(key, value->CreateDeepCopy());
-  }
-}
-}  // namespace
-
 std::unique_ptr<base::DictionaryValue>
-PolicyWatcher::StoreNewAndReturnChangedPolicies(
+PolicyWatcherImpl::StoreNewAndReturnChangedPolicies(
     std::unique_ptr<base::DictionaryValue> new_policies) {
   // Find the changed policies.
   std::unique_ptr<base::DictionaryValue> changed_policies(
@@ -285,9 +349,9 @@ PolicyWatcher::StoreNewAndReturnChangedPolicies(
   return changed_policies;
 }
 
-void PolicyWatcher::OnPolicyUpdated(const policy::PolicyNamespace& ns,
-                                    const policy::PolicyMap& previous,
-                                    const policy::PolicyMap& current) {
+void PolicyWatcherImpl::OnPolicyUpdated(const policy::PolicyNamespace& ns,
+                                        const policy::PolicyMap& previous,
+                                        const policy::PolicyMap& current) {
   std::unique_ptr<base::DictionaryValue> new_policies =
       CopyChromotingPoliciesIntoDictionary(current);
 
@@ -318,12 +382,18 @@ void PolicyWatcher::OnPolicyUpdated(const policy::PolicyNamespace& ns,
   policy_updated_callback_.Run(std::move(changed_policies));
 }
 
-void PolicyWatcher::OnPolicyServiceInitialized(policy::PolicyDomain domain) {
+void PolicyWatcherImpl::OnPolicyServiceInitialized(
+    policy::PolicyDomain domain) {
   policy::PolicyNamespace ns = GetPolicyNamespace();
   const policy::PolicyMap& current = policy_service_->GetPolicies(ns);
   OnPolicyUpdated(ns, current, current);
 }
 
+}  // namespace
+
+PolicyWatcher::PolicyWatcher() {}
+PolicyWatcher::~PolicyWatcher() {}
+
 std::unique_ptr<PolicyWatcher> PolicyWatcher::CreateFromPolicyLoader(
     std::unique_ptr<policy::AsyncPolicyLoader> async_policy_loader) {
   std::unique_ptr<policy::SchemaRegistry> schema_registry =
@@ -339,7 +409,7 @@ std::unique_ptr<PolicyWatcher> PolicyWatcher::CreateFromPolicyLoader(
       new policy::PolicyServiceImpl(providers));
 
   policy::PolicyService* borrowed_policy_service = policy_service.get();
-  return base::WrapUnique(new PolicyWatcher(
+  return base::WrapUnique(new PolicyWatcherImpl(
       borrowed_policy_service, std::move(policy_service),
       std::move(policy_provider), std::move(schema_registry)));
 }