Introduced a ForwardingPolicyProvider.

chrome/browser/extensions/api/storage/managed_value_store_cache.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/api/storage/managed_value_store_cache.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/logging.h"
-#include "base/memory/ref_counted.h"
-#include "base/message_loop/message_loop_proxy.h"
+#include "base/memory/weak_ptr.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/api/storage/policy_value_store.h"
 #include "chrome/browser/extensions/api/storage/settings_storage_factory.h"
 #include "chrome/browser/extensions/extension_prefs.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/policy/profile_policy_connector.h"
 #include "chrome/browser/policy/profile_policy_connector_factory.h"
+#include "chrome/browser/policy/schema_map.h"
 #include "chrome/browser/policy/schema_registry.h"
 #include "chrome/browser/policy/schema_registry_service.h"
 #include "chrome/browser/policy/schema_registry_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/value_store/value_store_change.h"
 #include "chrome/common/extensions/api/storage.h"
 #include "chrome/common/extensions/api/storage/storage_schema_manifest_handler.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_set.h"
 #include "components/policy/core/common/policy_namespace.h"
@@ skipping 15 matching lines @@
 namespace storage = api::storage;
 
 namespace {
 
 const char kLoadSchemasBackgroundTaskTokenName[] =
     "load_managed_storage_schemas_token";
 
 }  // namespace
 
 // This helper observes initialization of all the installed extensions and
-// subsequent loads and unloads, and keeps the PolicyService of the Profile
+// subsequent loads and unloads, and keeps the SchemaRegistry of the Profile
 // in sync with the current list of extensions. This allows the PolicyService
 // to fetch cloud policy for those extensions, and allows its providers to
 // selectively load only extension policy that has users.
 class ManagedValueStoreCache::ExtensionTracker
     : public content::NotificationObserver {
  public:
   explicit ExtensionTracker(Profile* profile);
   virtual ~ExtensionTracker() {}
 
   // NotificationObserver implementation:
@@ skipping 74 matching lines @@
   ExtensionSet::const_iterator it = added->begin();
   while (it != added->end()) {
     std::string to_remove;
     if (!UsesManagedStorage(*it))
       to_remove = (*it)->id();
     ++it;
     if (!to_remove.empty())
       added->Remove(to_remove);
   }
 
-  if (added->is_empty())
-    return;
-
   // Load the schema files in a background thread.
   BrowserThread::PostBlockingPoolSequencedTask(
       kLoadSchemasBackgroundTaskTokenName, FROM_HERE,
       base::Bind(&ExtensionTracker::LoadSchemas,
                  base::Passed(&added),
                  weak_factory_.GetWeakPtr()));
 }
 
 bool ManagedValueStoreCache::ExtensionTracker::UsesManagedStorage(
     const Extension* extension) const {
@@ skipping 39 matching lines @@
 
   BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
                           base::Bind(&ExtensionTracker::Register, self,
                                      base::Owned(components.release())));
 }
 
 void ManagedValueStoreCache::ExtensionTracker::Register(
     const policy::ComponentMap* components) {
   schema_registry_->RegisterComponents(policy::POLICY_DOMAIN_EXTENSIONS,
                                        *components);
+
+  // The first SetReady() call is performed after receiving
+  // NOTIFICATION_EXTENSIONS_READY, even if there are no managed extensions.
+  // It will trigger a loading of the initial policy for any managed
+  // extensions, and eventually the PolicyService will become ready for
+  // POLICY_DOMAIN_EXTENSIONS, and OnPolicyServiceInitialized() will be invoked.
+  // Subsequent calls to SetReady() are ignored.
+  schema_registry_->SetReady(policy::POLICY_DOMAIN_EXTENSIONS);
 }
 
 ManagedValueStoreCache::ManagedValueStoreCache(
     Profile* profile,
     const scoped_refptr<SettingsStorageFactory>& factory,
     const scoped_refptr<SettingsObserverList>& observers)
-    : weak_factory_(this),
-      weak_this_on_ui_(weak_factory_.GetWeakPtr()),
-      profile_(profile),
-      event_router_(ExtensionSystem::Get(profile)->event_router()),
+    : profile_(profile),
+      policy_service_(policy::ProfilePolicyConnectorFactory::GetForProfile(
+          profile)->policy_service()),
       storage_factory_(factory),
       observers_(observers),
       base_path_(profile->GetPath().AppendASCII(
           extensions::kManagedSettingsDirectoryName)) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  // |event_router_| can be NULL on unit_tests.
-  if (event_router_)
-    event_router_->RegisterObserver(this, storage::OnChanged::kEventName);
 
-  GetPolicyService()->AddObserver(policy::POLICY_DOMAIN_EXTENSIONS, this);
+  policy_service_->AddObserver(policy::POLICY_DOMAIN_EXTENSIONS, this);
 
   extension_tracker_.reset(new ExtensionTracker(profile_));
+
+  if (policy_service_->IsInitializationComplete(
+          policy::POLICY_DOMAIN_EXTENSIONS)) {
+    OnPolicyServiceInitialized(policy::POLICY_DOMAIN_EXTENSIONS);
+  }
 }
 
 ManagedValueStoreCache::~ManagedValueStoreCache() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(!event_router_);
   // Delete the PolicyValueStores on FILE.
   store_map_.clear();
 }
 
 void ManagedValueStoreCache::ShutdownOnUI() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  GetPolicyService()->RemoveObserver(policy::POLICY_DOMAIN_EXTENSIONS, this);
-  if (event_router_)
-    event_router_->UnregisterObserver(this);
-  event_router_ = NULL;
-  weak_factory_.InvalidateWeakPtrs();
+  policy_service_->RemoveObserver(policy::POLICY_DOMAIN_EXTENSIONS, this);
   extension_tracker_.reset();
 }
 
 void ManagedValueStoreCache::RunWithValueStoreForExtension(
     const StorageCallback& callback,
     scoped_refptr<const Extension> extension) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  PolicyValueStore* store = GetStoreFor(extension->id());
-  if (store) {
-    callback.Run(store);
-  } else {
-    // First time that an extension calls storage.managed.get(). Create the
-    // store and load it with the current policy, and don't send event
-    // notifications.
-    CreateStoreFor(
-        extension->id(),
-        false,
-        base::Bind(&ManagedValueStoreCache::RunWithValueStoreForExtension,
-                   base::Unretained(this),
-                   callback,
-                   extension));
-  }
+  callback.Run(GetStoreFor(extension->id()));
 }
 
 void ManagedValueStoreCache::DeleteStorageSoon(
     const std::string& extension_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  PolicyValueStore* store = GetStoreFor(extension_id);
-  if (!store) {
-    // It's possible that the store exists, but hasn't been loaded yet
-    // (because the extension is unloaded, for example). Open the database to
-    // clear it if it exists.
-    // TODO(joaodasilva): move this check to a ValueStore method.
-    if (base::DirectoryExists(base_path_.AppendASCII(extension_id))) {
-      CreateStoreFor(
-          extension_id,
-          false,
-          base::Bind(&ManagedValueStoreCache::DeleteStorageSoon,
-                     base::Unretained(this),
-                     extension_id));
-    }
-  } else {
-    store->DeleteStorage();
-    store_map_.erase(extension_id);
+  // It's possible that the store exists, but hasn't been loaded yet
+  // (because the extension is unloaded, for example). Open the database to
+  // clear it if it exists.
+  // TODO(joaodasilva): move this check to a ValueStore method.
+  if (!base::DirectoryExists(base_path_.AppendASCII(extension_id)))
+    return;
+  GetStoreFor(extension_id)->DeleteStorage();
+  store_map_.erase(extension_id);
+}
+
+void ManagedValueStoreCache::OnPolicyServiceInitialized(
+    policy::PolicyDomain domain) {

[not at google - send to devlin, 2013/11/13 00:30:18]

for consistency with this file: add a BrowserThread::UI assertion.

[Joao da Silva, 2013/11/13 08:56:47]

Done.

+  if (domain != policy::POLICY_DOMAIN_EXTENSIONS)
+    return;
+
+  // The PolicyService now has all the initial policies ready. Send policy
+  // for all the managed extensions to their backing stores now.
+  policy::SchemaRegistry* registry =
+      policy::SchemaRegistryServiceFactory::GetForContext(profile_);
+  const policy::ComponentMap* map = registry->schema_map()->GetComponents(
+      policy::POLICY_DOMAIN_EXTENSIONS);
+  if (!map)
+    return;
+
+  const policy::PolicyMap empty_map;
+  for (policy::ComponentMap::const_iterator it = map->begin();
+       it != map->end(); ++it) {
+    const policy::PolicyNamespace ns(policy::POLICY_DOMAIN_EXTENSIONS,
+                                     it->first);
+    // If there is no policy for |ns| then this will clear the previous store,
+    // if there is one.
+    OnPolicyUpdated(ns, empty_map, policy_service_->GetPolicies(ns));

[not at google - send to devlin, 2013/11/13 00:30:18]

I don't know what a "component" is here, but just checking it's not a problem
that you're going to be posting a bunch of stuff to the FILE thread like this,
when it could be done all at once.

[Joao da Silva, 2013/11/13 08:56:47]

This for() loop is iterating over the list of extensions that declare a
managed-storage-schema in their manifest. For non-managed installations this is
most likely 0, in an enterprise that loves managed extensions it could be around
10 or so.

   }
 }
 
 void ManagedValueStoreCache::OnPolicyUpdated(const policy::PolicyNamespace& ns,
                                              const policy::PolicyMap& previous,
                                              const policy::PolicyMap& current) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (!policy_service_->IsInitializationComplete(
+           policy::POLICY_DOMAIN_EXTENSIONS)) {

[not at google - send to devlin, 2013/11/13 00:30:18]

Why not check that ns != POLICY_DOMAIN_EXTENSIONS instead?

[Joao da Silva, 2013/11/13 08:56:47]

On line 234 this starts observing updates to POLICY_DOMAIN_EXTENSIONS, so
|ns.domain| is always going to have that value.

This check is meant to skip OnPolicyUpdated() notifications that come before all
the policy providers are ready (e.g. if a provider loads policy for an extension
an publishes it, but before a 2nd provider is ready). Once all of them are ready
then the policies are merged, and some providers may override the others.

+    // OnPolicyUpdated is called whenever a policy changes, but it doesn't
+    // mean that all the policy providers are ready; wait until we get the
+    // final policy values before passing them to the store.
+    return;
+  }
+
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
       base::Bind(&ManagedValueStoreCache::UpdatePolicyOnFILE,
                  base::Unretained(this),
                  ns.component_id,
                  base::Passed(current.DeepCopy())));
 }
 
 void ManagedValueStoreCache::UpdatePolicyOnFILE(
     const std::string& extension_id,
     scoped_ptr<policy::PolicyMap> current_policy) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  PolicyValueStore* store = GetStoreFor(extension_id);
-  if (!store) {
-    // The extension hasn't executed any storage.managed.* calls, and isn't
-    // listening for onChanged() either. Ignore this notification in that case.
-    return;
-  }
-  // Update the policy on the backing store, and fire notifications if it
-  // changed.
-  store->SetCurrentPolicy(*current_policy, true);
-}
-
-void ManagedValueStoreCache::OnListenerAdded(
-    const EventListenerInfo& details) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK_EQ(std::string(storage::OnChanged::kEventName), details.event_name);
-  // This is invoked on several occasions:
-  //
-  // 1. when an extension first registers to observe storage.onChanged; in this
-  //    case the backend doesn't have any previous data persisted, and it won't
-  //    trigger a notification.
-  //
-  // 2. when the browser starts up and all existing extensions re-register for
-  //    the onChanged event. In this case, if the current policy differs from
-  //    the persisted version then a notification will be sent.
-  //
-  // 3. a policy update just occurred and sent a notification, and an extension
-  //    with EventPages that is observing onChanged just woke up and registed
-  //    again. In this case the policy update already persisted the current
-  //    policy version, and |store| already exists.
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
-      base::Bind(&ManagedValueStoreCache::CreateForExtensionOnFILE,
-                 base::Unretained(this),
-                 details.extension_id));
-}
-
-void ManagedValueStoreCache::CreateForExtensionOnFILE(
-    const std::string& extension_id) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  PolicyValueStore* store = GetStoreFor(extension_id);
-  if (!store)
-    CreateStoreFor(extension_id, true, base::Closure());
+  GetStoreFor(extension_id)->SetCurrentPolicy(*current_policy);
 }
 
 PolicyValueStore* ManagedValueStoreCache::GetStoreFor(
     const std::string& extension_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
   PolicyValueStoreMap::iterator it = store_map_.find(extension_id);
-  if (it == store_map_.end())
-    return NULL;
-  return it->second.get();
-}
+  if (it != store_map_.end())
+    return it->second.get();
 
-void ManagedValueStoreCache::CreateStoreFor(
-    const std::string& extension_id,
-    bool notify_if_changed,
-    const base::Closure& continuation) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(!GetStoreFor(extension_id));
-  // Creating or loading an existing database requires an immediate update
-  // with the current policy for the corresponding extension, which must be
-  // retrieved on UI.
-  BrowserThread::PostTask(
-      BrowserThread::UI, FROM_HERE,
-      base::Bind(&ManagedValueStoreCache::GetInitialPolicy,
-                 weak_this_on_ui_,
-                 extension_id,
-                 notify_if_changed,
-                 continuation));
-}
+  // Create the store now, and serve the cached policy until the PolicyService
+  // sends updated values.
+  PolicyValueStore* store = new PolicyValueStore(
+      extension_id,
+      observers_,
+      make_scoped_ptr(storage_factory_->Create(base_path_, extension_id)));
+  store_map_[extension_id] = make_linked_ptr(store);
 
-void ManagedValueStoreCache::GetInitialPolicy(
-    const std::string& extension_id,
-    bool notify_if_changed,
-    const base::Closure& continuation) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  policy::PolicyService* policy_service = GetPolicyService();
-
-  // If initialization of POLICY_DOMAIN_EXTENSIONS isn't complete then all the
-  // policies served are empty; let the extension see what's cached in LevelDB
-  // in that case. The PolicyService will issue notifications once new policies
-  // are ready.
-  scoped_ptr<policy::PolicyMap> policy;
-  if (policy_service->IsInitializationComplete(
-          policy::POLICY_DOMAIN_EXTENSIONS)) {
-    policy::PolicyNamespace ns(policy::POLICY_DOMAIN_EXTENSIONS, extension_id);
-    policy = policy_service->GetPolicies(ns).DeepCopy();
-  }
-
-  // Now post back to FILE to create the database.
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
-      base::Bind(&ManagedValueStoreCache::CreateStoreWithInitialPolicy,
-                 base::Unretained(this),
-                 extension_id,
-                 notify_if_changed,
-                 base::Passed(&policy),
-                 continuation));
-}
-
-void ManagedValueStoreCache::CreateStoreWithInitialPolicy(
-    const std::string& extension_id,
-    bool notify_if_changed,
-    scoped_ptr<policy::PolicyMap> initial_policy,
-    const base::Closure& continuation) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  // If a 2nd call to CreateStoreFor() is issued before the 1st gets to execute
-  // its UI task, then the 2nd will enter this function but the store has
-  // already been created. Check for that.
-  PolicyValueStore* store = GetStoreFor(extension_id);
-
-  if (!store) {
-    // Create it now.
-
-    // If the database doesn't exist yet then this is the initial install,
-    // and no notifications should be issued in that case.
-    // TODO(joaodasilva): move this check to a ValueStore method.
-    if (!base::DirectoryExists(base_path_.AppendASCII(extension_id)))
-      notify_if_changed = false;
-
-    store = new PolicyValueStore(
-        extension_id,
-        observers_,
-        make_scoped_ptr(storage_factory_->Create(base_path_, extension_id)));
-    store_map_[extension_id] = make_linked_ptr(store);
-  }
-
-  // Send the latest policy to the store, if it's already available.
-  if (initial_policy)
-    store->SetCurrentPolicy(*initial_policy, notify_if_changed);
-
-  // And finally resume from where this process started.
-  if (!continuation.is_null())
-    continuation.Run();
-}
-
-policy::PolicyService* ManagedValueStoreCache::GetPolicyService() {
-  policy::ProfilePolicyConnector* connector =
-      policy::ProfilePolicyConnectorFactory::GetForProfile(profile_);
-  return connector->policy_service();
+  return store;
 }
 
 }  // namespace extensions