Persist sessionStorage on disk.

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 d525462ee2ab28b0ab892fc5520086d7e1ffcada..c7ab9fd53444d69e269dafbf1c1b18ed258aeee9 100644
--- a/content/browser/dom_storage/dom_storage_context_impl.cc
+++ b/content/browser/dom_storage/dom_storage_context_impl.cc
@@ -24,6 +24,7 @@ using dom_storage::DomStorageWorkerPoolTaskRunner;
 namespace {
 
 const char kLocalStorageDirectory[] = "Local Storage";
+const char kSessionStorageDirectory[] = "Session Storage";
 
 void InvokeUsageInfoCallbackHelper(
       const DOMStorageContext::GetUsageInfoCallback& callback,
@@ -48,14 +49,14 @@ void GetUsageInfoHelper(
 
 DOMStorageContextImpl::DOMStorageContextImpl(
     const FilePath& data_path,
-    quota::SpecialStoragePolicy* special_storage_policy) {
+    quota::SpecialStoragePolicy* special_storage_policy,
+    bool save_session_storage_on_disk) {
   base::SequencedWorkerPool* worker_pool = BrowserThread::GetBlockingPool();
-  // TODO(marja): Pass a nonempty session storage directory when session storage
-  // is backed on disk.
   context_ = new dom_storage::DomStorageContext(
       data_path.empty() ?
           data_path : data_path.AppendASCII(kLocalStorageDirectory),
-      FilePath(),  // Empty session storage directory.
+      (data_path.empty() || !save_session_storage_on_disk) ?
+          FilePath() : data_path.AppendASCII(kSessionStorageDirectory),
       special_storage_policy,
       new DomStorageWorkerPoolTaskRunner(
           worker_pool,
@@ -92,6 +93,15 @@ DOMStorageContextImpl::RecreateSessionStorage(
       new SessionStorageNamespaceImpl(this, persistent_id));
 }
 
+void DOMStorageContextImpl::StartScavengingUnusedSessionStorage() {
+  DCHECK(context_);
+  context_->task_runner()->PostShutdownBlockingTask(
+      FROM_HERE,
+      DomStorageTaskRunner::PRIMARY_SEQUENCE,
+      base::Bind(&DomStorageContext::StartScavengingUnusedSessionStorage,
+                 context_));
+}
+
 void DOMStorageContextImpl::PurgeMemory() {
   DCHECK(context_);
   context_->task_runner()->PostShutdownBlockingTask(