Move webkit/{browser,common}/dom_storage into content/

content/browser/dom_storage/dom_storage_context_impl.cc

Index: content/browser/dom_storage/dom_storage_context_impl.cc
diff --git a/content/browser/dom_storage/dom_storage_context_impl.cc b/content/browser/dom_storage/dom_storage_context_impl.cc
index f790ecd8001a750bec29f8337cd165f311fd8745..dd1f33e847fb13702496061685d6f85b7863ad3c 100644
--- a/content/browser/dom_storage/dom_storage_context_impl.cc
+++ b/content/browser/dom_storage/dom_storage_context_impl.cc
@@ -6,171 +6,417 @@
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
-#include "base/files/file_path.h"
-#include "base/message_loop/message_loop_proxy.h"
-#include "content/browser/dom_storage/session_storage_namespace_impl.h"
-#include "content/public/browser/browser_thread.h"
-#include "webkit/browser/dom_storage/dom_storage_area.h"
-#include "webkit/browser/dom_storage/dom_storage_context.h"
-#include "webkit/browser/dom_storage/dom_storage_task_runner.h"
-
-using dom_storage::DomStorageArea;
-using dom_storage::DomStorageContext;
-using dom_storage::DomStorageTaskRunner;
-using dom_storage::DomStorageWorkerPoolTaskRunner;
+#include "base/file_util.h"
+#include "base/files/file_enumerator.h"
+#include "base/guid.h"
+#include "base/location.h"
+#include "base/time/time.h"
+#include "content/browser/dom_storage/dom_storage_area.h"
+#include "content/browser/dom_storage/dom_storage_database.h"
+#include "content/browser/dom_storage/dom_storage_namespace.h"
+#include "content/browser/dom_storage/dom_storage_task_runner.h"
+#include "content/browser/dom_storage/session_storage_database.h"
+#include "content/common/dom_storage/dom_storage_types.h"
+#include "content/public/browser/dom_storage_context.h"
+#include "content/public/browser/local_storage_usage_info.h"
+#include "content/public/browser/session_storage_usage_info.h"
+#include "webkit/browser/quota/special_storage_policy.h"
 
 namespace content {
-namespace {
 
-const char kLocalStorageDirectory[] = "Local Storage";
-const char kSessionStorageDirectory[] = "Session Storage";
+static const int kSessionStoraceScavengingSeconds = 60;
 
-void InvokeLocalStorageUsageCallbackHelper(
-      const DOMStorageContext::GetLocalStorageUsageCallback& callback,
-      const std::vector<dom_storage::LocalStorageUsageInfo>* infos) {
-  callback.Run(*infos);
+DOMStorageContextImpl::DOMStorageContextImpl(
+    const base::FilePath& localstorage_directory,
+    const base::FilePath& sessionstorage_directory,
+    quota::SpecialStoragePolicy* special_storage_policy,
+    DOMStorageTaskRunner* task_runner)
+    : localstorage_directory_(localstorage_directory),
+      sessionstorage_directory_(sessionstorage_directory),
+      task_runner_(task_runner),
+      is_shutdown_(false),
+      force_keep_session_state_(false),
+      special_storage_policy_(special_storage_policy),
+      scavenging_started_(false) {
+  // AtomicSequenceNum starts at 0 but we want to start session
+  // namespace ids at one since zero is reserved for the
+  // kLocalStorageNamespaceId.
+  session_id_sequence_.GetNext();
 }
 
-void GetLocalStorageUsageHelper(
-    base::MessageLoopProxy* reply_loop,
-    DomStorageContext* context,
-    const DOMStorageContext::GetLocalStorageUsageCallback& callback) {
-  std::vector<dom_storage::LocalStorageUsageInfo>* infos =
-      new std::vector<dom_storage::LocalStorageUsageInfo>;
-  context->GetLocalStorageUsage(infos, true);
-  reply_loop->PostTask(
-      FROM_HERE,
-      base::Bind(&InvokeLocalStorageUsageCallbackHelper,
-                 callback, base::Owned(infos)));
+DOMStorageContextImpl::~DOMStorageContextImpl() {
+  if (session_storage_database_.get()) {
+    // SessionStorageDatabase shouldn't be deleted right away: deleting it will
+    // potentially involve waiting in leveldb::DBImpl::~DBImpl, and waiting
+    // shouldn't happen on this thread.
+    SessionStorageDatabase* to_release = session_storage_database_.get();
+    to_release->AddRef();
+    session_storage_database_ = NULL;
+    task_runner_->PostShutdownBlockingTask(
+        FROM_HERE,
+        DOMStorageTaskRunner::COMMIT_SEQUENCE,
+        base::Bind(&SessionStorageDatabase::Release,
+                   base::Unretained(to_release)));
+  }
 }
 
-void InvokeSessionStorageUsageCallbackHelper(
-      const DOMStorageContext::GetSessionStorageUsageCallback& callback,
-      const std::vector<dom_storage::SessionStorageUsageInfo>* infos) {
-  callback.Run(*infos);
+DOMStorageNamespace* DOMStorageContextImpl::GetStorageNamespace(
+    int64 namespace_id) {
+  if (is_shutdown_)
+    return NULL;
+  StorageNamespaceMap::iterator found = namespaces_.find(namespace_id);
+  if (found == namespaces_.end()) {
+    if (namespace_id == kLocalStorageNamespaceId) {
+      if (!localstorage_directory_.empty()) {
+        if (!file_util::CreateDirectory(localstorage_directory_)) {
+          LOG(ERROR) << "Failed to create 'Local Storage' directory,"
+                        " falling back to in-memory only.";
+          localstorage_directory_ = base::FilePath();
+        }
+      }
+      DOMStorageNamespace* local =
+          new DOMStorageNamespace(localstorage_directory_, task_runner_.get());
+      namespaces_[kLocalStorageNamespaceId] = local;
+      return local;
+    }
+    return NULL;
+  }
+  return found->second.get();
 }
 
-void GetSessionStorageUsageHelper(
-    base::MessageLoopProxy* reply_loop,
-    DomStorageContext* context,
-    const DOMStorageContext::GetSessionStorageUsageCallback& callback) {
-  std::vector<dom_storage::SessionStorageUsageInfo>* infos =
-      new std::vector<dom_storage::SessionStorageUsageInfo>;
-  context->GetSessionStorageUsage(infos);
-  reply_loop->PostTask(
-      FROM_HERE,
-      base::Bind(&InvokeSessionStorageUsageCallbackHelper,
-                 callback, base::Owned(infos)));
+void DOMStorageContextImpl::GetLocalStorageUsage(
+    std::vector<LocalStorageUsageInfo>* infos,
+    bool include_file_info) {
+  if (localstorage_directory_.empty())
+    return;
+  base::FileEnumerator enumerator(localstorage_directory_, false,
+                                  base::FileEnumerator::FILES);
+  for (base::FilePath path = enumerator.Next(); !path.empty();
+       path = enumerator.Next()) {
+    if (path.MatchesExtension(DOMStorageArea::kDatabaseFileExtension)) {
+      LocalStorageUsageInfo info;
+      info.origin = DOMStorageArea::OriginFromDatabaseFileName(path);
+      if (include_file_info) {
+        base::FileEnumerator::FileInfo find_info = enumerator.GetInfo();
+        info.data_size = find_info.GetSize();
+        info.last_modified = find_info.GetLastModifiedTime();
+      }
+      infos->push_back(info);
+    }
+  }
 }
 
-}  // namespace
+void DOMStorageContextImpl::GetSessionStorageUsage(
+    std::vector<SessionStorageUsageInfo>* infos) {
+  if (!session_storage_database_.get())
+    return;
+  std::map<std::string, std::vector<GURL> > namespaces_and_origins;
+  session_storage_database_->ReadNamespacesAndOrigins(
+      &namespaces_and_origins);
+  for (std::map<std::string, std::vector<GURL> >::const_iterator it =
+           namespaces_and_origins.begin();
+       it != namespaces_and_origins.end(); ++it) {
+    for (std::vector<GURL>::const_iterator origin_it = it->second.begin();
+         origin_it != it->second.end(); ++origin_it) {
+      SessionStorageUsageInfo info;
+      info.persistent_namespace_id = it->first;
+      info.origin = *origin_it;
+      infos->push_back(info);
+    }
+  }
+}
 
-DOMStorageContextImpl::DOMStorageContextImpl(
-    const base::FilePath& data_path,
-    quota::SpecialStoragePolicy* special_storage_policy) {
-  base::SequencedWorkerPool* worker_pool = BrowserThread::GetBlockingPool();
-  context_ = new dom_storage::DomStorageContext(
-      data_path.empty() ? data_path
-                        : data_path.AppendASCII(kLocalStorageDirectory),
-      data_path.empty() ? data_path
-                        : data_path.AppendASCII(kSessionStorageDirectory),
-      special_storage_policy,
-      new DomStorageWorkerPoolTaskRunner(
-          worker_pool,
-          worker_pool->GetNamedSequenceToken("dom_storage_primary"),
-          worker_pool->GetNamedSequenceToken("dom_storage_commit"),
-          BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO)
-              .get()));
+void DOMStorageContextImpl::DeleteLocalStorage(const GURL& origin) {
+  DCHECK(!is_shutdown_);
+  DOMStorageNamespace* local = GetStorageNamespace(kLocalStorageNamespaceId);
+  local->DeleteLocalStorageOrigin(origin);
+  // Synthesize a 'cleared' event if the area is open so CachedAreas in
+  // renderers get emptied out too.
+  DOMStorageArea* area = local->GetOpenStorageArea(origin);
+  if (area)
+    NotifyAreaCleared(area, origin);
 }
 
-DOMStorageContextImpl::~DOMStorageContextImpl() {
+void DOMStorageContextImpl::DeleteSessionStorage(
+    const SessionStorageUsageInfo& usage_info) {
+  DCHECK(!is_shutdown_);
+  DOMStorageNamespace* dom_storage_namespace = NULL;
+  std::map<std::string, int64>::const_iterator it =
+      persistent_namespace_id_to_namespace_id_.find(
+          usage_info.persistent_namespace_id);
+  if (it != persistent_namespace_id_to_namespace_id_.end()) {
+    dom_storage_namespace = GetStorageNamespace(it->second);
+  } else {
+    int64 namespace_id = AllocateSessionId();
+    CreateSessionNamespace(namespace_id, usage_info.persistent_namespace_id);
+    dom_storage_namespace = GetStorageNamespace(namespace_id);
+  }
+  dom_storage_namespace->DeleteSessionStorageOrigin(usage_info.origin);
+  // Synthesize a 'cleared' event if the area is open so CachedAreas in
+  // renderers get emptied out too.
+  DOMStorageArea* area =
+      dom_storage_namespace->GetOpenStorageArea(usage_info.origin);
+  if (area)
+    NotifyAreaCleared(area, usage_info.origin);
 }
 
-void DOMStorageContextImpl::GetLocalStorageUsage(
-    const GetLocalStorageUsageCallback& callback) {
-  DCHECK(context_.get());
-  context_->task_runner()
-      ->PostShutdownBlockingTask(FROM_HERE,
-                                 DomStorageTaskRunner::PRIMARY_SEQUENCE,
-                                 base::Bind(&GetLocalStorageUsageHelper,
-                                            base::MessageLoopProxy::current(),
-                                            context_,
-                                            callback));
+void DOMStorageContextImpl::PurgeMemory() {
+  // We can only purge memory from the local storage namespace
+  // which is backed by disk.
+  // TODO(marja): Purge sessionStorage, too. (Requires changes to the FastClear
+  // functionality.)
+  StorageNamespaceMap::iterator found =
+      namespaces_.find(kLocalStorageNamespaceId);
+  if (found != namespaces_.end())
+    found->second->PurgeMemory(DOMStorageNamespace::PURGE_AGGRESSIVE);
 }
 
-void DOMStorageContextImpl::GetSessionStorageUsage(
-    const GetSessionStorageUsageCallback& callback) {
-  DCHECK(context_.get());
-  context_->task_runner()
-      ->PostShutdownBlockingTask(FROM_HERE,
-                                 DomStorageTaskRunner::PRIMARY_SEQUENCE,
-                                 base::Bind(&GetSessionStorageUsageHelper,
-                                            base::MessageLoopProxy::current(),
-                                            context_,
-                                            callback));
+void DOMStorageContextImpl::Shutdown() {
+  is_shutdown_ = true;
+  StorageNamespaceMap::const_iterator it = namespaces_.begin();
+  for (; it != namespaces_.end(); ++it)
+    it->second->Shutdown();
+
+  if (localstorage_directory_.empty() && !session_storage_database_.get())
+    return;
+
+  // Respect the content policy settings about what to
+  // keep and what to discard.
+  if (force_keep_session_state_)
+    return;  // Keep everything.
+
+  bool has_session_only_origins =
+      special_storage_policy_.get() &&
+      special_storage_policy_->HasSessionOnlyOrigins();
+
+  if (has_session_only_origins) {
+    // We may have to delete something. We continue on the
+    // commit sequence after area shutdown tasks have cycled
+    // thru that sequence (and closed their database files).
+    bool success = task_runner_->PostShutdownBlockingTask(
+        FROM_HERE,
+        DOMStorageTaskRunner::COMMIT_SEQUENCE,
+        base::Bind(&DOMStorageContextImpl::ClearSessionOnlyOrigins, this));
+    DCHECK(success);
+  }
 }
 
-void DOMStorageContextImpl::DeleteLocalStorage(const GURL& origin) {
-  DCHECK(context_.get());
-  context_->task_runner()->PostShutdownBlockingTask(
-      FROM_HERE,
-      DomStorageTaskRunner::PRIMARY_SEQUENCE,
-      base::Bind(&DomStorageContext::DeleteLocalStorage, context_, origin));
+void DOMStorageContextImpl::AddEventObserver(EventObserver* observer) {
+  event_observers_.AddObserver(observer);
 }
 
-void DOMStorageContextImpl::DeleteSessionStorage(
-    const dom_storage::SessionStorageUsageInfo& usage_info) {
-  DCHECK(context_.get());
-  context_->task_runner()->PostShutdownBlockingTask(
-      FROM_HERE,
-      DomStorageTaskRunner::PRIMARY_SEQUENCE,
-      base::Bind(
-          &DomStorageContext::DeleteSessionStorage, context_, usage_info));
+void DOMStorageContextImpl::RemoveEventObserver(EventObserver* observer) {
+  event_observers_.RemoveObserver(observer);
 }
 
-void DOMStorageContextImpl::SetSaveSessionStorageOnDisk() {
-  DCHECK(context_.get());
-  context_->SetSaveSessionStorageOnDisk();
+void DOMStorageContextImpl::NotifyItemSet(
+    const DOMStorageArea* area,
+    const base::string16& key,
+    const base::string16& new_value,
+    const base::NullableString16& old_value,
+    const GURL& page_url) {
+  FOR_EACH_OBSERVER(
+      EventObserver, event_observers_,
+      OnDOMStorageItemSet(area, key, new_value, old_value, page_url));
 }
 
-scoped_refptr<SessionStorageNamespace>
-DOMStorageContextImpl::RecreateSessionStorage(
-    const std::string& persistent_id) {
-  return scoped_refptr<SessionStorageNamespace>(
-      new SessionStorageNamespaceImpl(this, persistent_id));
+void DOMStorageContextImpl::NotifyItemRemoved(
+    const DOMStorageArea* area,
+    const base::string16& key,
+    const base::string16& old_value,
+    const GURL& page_url) {
+  FOR_EACH_OBSERVER(
+      EventObserver, event_observers_,
+      OnDOMStorageItemRemoved(area, key, old_value, page_url));
+}
+
+void DOMStorageContextImpl::NotifyAreaCleared(
+    const DOMStorageArea* area,
+    const GURL& page_url) {
+  FOR_EACH_OBSERVER(
+      EventObserver, event_observers_,
+      OnDOMStorageAreaCleared(area, page_url));
+}
+
+std::string DOMStorageContextImpl::AllocatePersistentSessionId() {
+  std::string guid = base::GenerateGUID();
+  std::replace(guid.begin(), guid.end(), '-', '_');
+  return guid;
+}
+
+void DOMStorageContextImpl::CreateSessionNamespace(
+    int64 namespace_id,
+    const std::string& persistent_namespace_id) {
+  if (is_shutdown_)
+    return;
+  DCHECK(namespace_id != kLocalStorageNamespaceId);
+  DCHECK(namespaces_.find(namespace_id) == namespaces_.end());
+  namespaces_[namespace_id] = new DOMStorageNamespace(
+      namespace_id, persistent_namespace_id, session_storage_database_.get(),
+      task_runner_.get());
+  persistent_namespace_id_to_namespace_id_[persistent_namespace_id] =
+      namespace_id;
+}
+
+void DOMStorageContextImpl::DeleteSessionNamespace(
+    int64 namespace_id, bool should_persist_data) {
+  DCHECK_NE(kLocalStorageNamespaceId, namespace_id);
+  StorageNamespaceMap::const_iterator it = namespaces_.find(namespace_id);
+  if (it == namespaces_.end())
+    return;
+  std::string persistent_namespace_id = it->second->persistent_namespace_id();
+  if (session_storage_database_.get()) {
+    if (!should_persist_data) {
+      task_runner_->PostShutdownBlockingTask(
+          FROM_HERE,
+          DOMStorageTaskRunner::COMMIT_SEQUENCE,
+          base::Bind(
+              base::IgnoreResult(&SessionStorageDatabase::DeleteNamespace),
+              session_storage_database_,
+              persistent_namespace_id));
+    } else {
+      // Ensure that the data gets committed before we shut down.
+      it->second->Shutdown();
+      if (!scavenging_started_) {
+        // Protect the persistent namespace ID from scavenging.
+        protected_persistent_session_ids_.insert(persistent_namespace_id);
+      }
+    }
+  }
+  persistent_namespace_id_to_namespace_id_.erase(persistent_namespace_id);
+  namespaces_.erase(namespace_id);
+}
+
+void DOMStorageContextImpl::CloneSessionNamespace(
+    int64 existing_id, int64 new_id,
+    const std::string& new_persistent_id) {
+  if (is_shutdown_)
+    return;
+  DCHECK_NE(kLocalStorageNamespaceId, existing_id);
+  DCHECK_NE(kLocalStorageNamespaceId, new_id);
+  StorageNamespaceMap::iterator found = namespaces_.find(existing_id);
+  if (found != namespaces_.end())
+    namespaces_[new_id] = found->second->Clone(new_id, new_persistent_id);
+  else
+    CreateSessionNamespace(new_id, new_persistent_id);
+}
+
+void DOMStorageContextImpl::ClearSessionOnlyOrigins() {
+  if (!localstorage_directory_.empty()) {
+    std::vector<LocalStorageUsageInfo> infos;
+    const bool kDontIncludeFileInfo = false;
+    GetLocalStorageUsage(&infos, kDontIncludeFileInfo);
+    for (size_t i = 0; i < infos.size(); ++i) {
+      const GURL& origin = infos[i].origin;
+      if (special_storage_policy_->IsStorageProtected(origin))
+        continue;
+      if (!special_storage_policy_->IsStorageSessionOnly(origin))
+        continue;
+
+      base::FilePath database_file_path = localstorage_directory_.Append(
+          DOMStorageArea::DatabaseFileNameFromOrigin(origin));
+      sql::Connection::Delete(database_file_path);
+    }
+  }
+  if (session_storage_database_.get()) {
+    std::vector<SessionStorageUsageInfo> infos;
+    GetSessionStorageUsage(&infos);
+    for (size_t i = 0; i < infos.size(); ++i) {
+      const GURL& origin = infos[i].origin;
+      if (special_storage_policy_->IsStorageProtected(origin))
+        continue;
+      if (!special_storage_policy_->IsStorageSessionOnly(origin))
+        continue;
+      session_storage_database_->DeleteArea(infos[i].persistent_namespace_id,
+                                            origin);
+    }
+  }
+}
+
+void DOMStorageContextImpl::SetSaveSessionStorageOnDisk() {
+  DCHECK(namespaces_.empty());
+  if (!sessionstorage_directory_.empty()) {
+    session_storage_database_ = new SessionStorageDatabase(
+        sessionstorage_directory_);
+  }
 }
 
 void DOMStorageContextImpl::StartScavengingUnusedSessionStorage() {
-  DCHECK(context_.get());
-  context_->task_runner()->PostShutdownBlockingTask(
-      FROM_HERE,
-      DomStorageTaskRunner::PRIMARY_SEQUENCE,
-      base::Bind(&DomStorageContext::StartScavengingUnusedSessionStorage,
-                 context_));
+  if (session_storage_database_.get()) {
+    task_runner_->PostDelayedTask(
+        FROM_HERE, base::Bind(&DOMStorageContextImpl::FindUnusedNamespaces,
+                              this),
+        base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
+  }
 }
 
-void DOMStorageContextImpl::PurgeMemory() {
-  DCHECK(context_.get());
-  context_->task_runner()->PostShutdownBlockingTask(
-      FROM_HERE,
-      DomStorageTaskRunner::PRIMARY_SEQUENCE,
-      base::Bind(&DomStorageContext::PurgeMemory, context_));
+void DOMStorageContextImpl::FindUnusedNamespaces() {
+  DCHECK(session_storage_database_.get());
+  if (scavenging_started_)
+    return;
+  scavenging_started_ = true;
+  std::set<std::string> namespace_ids_in_use;
+  for (StorageNamespaceMap::const_iterator it = namespaces_.begin();
+       it != namespaces_.end(); ++it)
+    namespace_ids_in_use.insert(it->second->persistent_namespace_id());
+  std::set<std::string> protected_persistent_session_ids;
+  protected_persistent_session_ids.swap(protected_persistent_session_ids_);
+  task_runner_->PostShutdownBlockingTask(
+      FROM_HERE, DOMStorageTaskRunner::COMMIT_SEQUENCE,
+      base::Bind(
+          &DOMStorageContextImpl::FindUnusedNamespacesInCommitSequence,
+          this, namespace_ids_in_use, protected_persistent_session_ids));
 }
 
-void DOMStorageContextImpl::SetForceKeepSessionState() {
-  DCHECK(context_.get());
-  context_->task_runner()->PostShutdownBlockingTask(
-      FROM_HERE,
-      DomStorageTaskRunner::PRIMARY_SEQUENCE,
-      base::Bind(&DomStorageContext::SetForceKeepSessionState, context_));
+void DOMStorageContextImpl::FindUnusedNamespacesInCommitSequence(
+    const std::set<std::string>& namespace_ids_in_use,
+    const std::set<std::string>& protected_persistent_session_ids) {
+  DCHECK(session_storage_database_.get());
+  // Delete all namespaces which don't have an associated DOMStorageNamespace
+  // alive.
+  std::map<std::string, std::vector<GURL> > namespaces_and_origins;
+  session_storage_database_->ReadNamespacesAndOrigins(&namespaces_and_origins);
+  for (std::map<std::string, std::vector<GURL> >::const_iterator it =
+           namespaces_and_origins.begin();
+       it != namespaces_and_origins.end(); ++it) {
+    if (namespace_ids_in_use.find(it->first) == namespace_ids_in_use.end() &&
+        protected_persistent_session_ids.find(it->first) ==
+        protected_persistent_session_ids.end()) {
+      deletable_persistent_namespace_ids_.push_back(it->first);
+    }
+  }
+  if (!deletable_persistent_namespace_ids_.empty()) {
+    task_runner_->PostDelayedTask(
+        FROM_HERE, base::Bind(
+            &DOMStorageContextImpl::DeleteNextUnusedNamespace,
+            this),
+        base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
+  }
 }
 
-void DOMStorageContextImpl::Shutdown() {
-  DCHECK(context_.get());
-  context_->task_runner()->PostShutdownBlockingTask(
-      FROM_HERE,
-      DomStorageTaskRunner::PRIMARY_SEQUENCE,
-      base::Bind(&DomStorageContext::Shutdown, context_));
+void DOMStorageContextImpl::DeleteNextUnusedNamespace() {
+  if (is_shutdown_)
+    return;
+  task_runner_->PostShutdownBlockingTask(
+        FROM_HERE, DOMStorageTaskRunner::COMMIT_SEQUENCE,
+        base::Bind(
+            &DOMStorageContextImpl::DeleteNextUnusedNamespaceInCommitSequence,
+            this));
+}
+
+void DOMStorageContextImpl::DeleteNextUnusedNamespaceInCommitSequence() {
+  if (deletable_persistent_namespace_ids_.empty())
+    return;
+  const std::string& persistent_id = deletable_persistent_namespace_ids_.back();
+  session_storage_database_->DeleteNamespace(persistent_id);
+  deletable_persistent_namespace_ids_.pop_back();
+  if (!deletable_persistent_namespace_ids_.empty()) {
+    task_runner_->PostDelayedTask(
+        FROM_HERE, base::Bind(
+            &DOMStorageContextImpl::DeleteNextUnusedNamespace,
+            this),
+        base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
+  }
 }
 
 }  // namespace content