Move SessionStorageNamespace entirely into NavigationController and support StoragePartitions.

chrome/browser/instant/instant_loader.cc

Index: chrome/browser/instant/instant_loader.cc
diff --git a/chrome/browser/instant/instant_loader.cc b/chrome/browser/instant/instant_loader.cc
index 41c9c856daa4abdaf84ed53a3b6c399b34c49ead..3fa6b74521287eec115d0dbff2b5612fbd1914b7 100644
--- a/chrome/browser/instant/instant_loader.cc
+++ b/chrome/browser/instant/instant_loader.cc
@@ -93,7 +93,12 @@ void AddPreviewUsageForHistogram(TemplateURLID template_url_id,
 }
 
 SessionStorageNamespace* GetSessionStorageNamespace(TabContents* tab) {
-  return tab->web_contents()->GetController().GetSessionStorageNamespace();
+  // TODO(ajwong): This is wrong because it assumes a default
+  // SessionStorageNamespace for a TabContents.
+  //
+  // http://crbug.com/140612
+  return tab->web_contents()->GetController()
+      .GetDefaultSessionStorageNamespace();
 }
 
 }  // namespace
@@ -851,6 +856,8 @@ TabContents* InstantLoader::ReleasePreviewContents(
       type == INSTANT_COMMIT_DESTROY ? PREVIEW_DELETED : PREVIEW_COMMITTED,
       group_);
   if (type != INSTANT_COMMIT_DESTROY) {
+    // This tracks the number of times a committed preview page destroys the
+    // Session Storage for the tab.
     base::Histogram* histogram = base::LinearHistogram::FactoryGet(
         "Instant.SessionStorageNamespace" + group_, 1, 2, 3,
         base::Histogram::kUmaTargetedHistogramFlag);
@@ -1144,7 +1151,7 @@ void InstantLoader::SetupPreviewContents(TabContents* tab_contents) {
 
 void InstantLoader::CreatePreviewContents(TabContents* tab_contents) {
   WebContents* new_contents = WebContents::Create(
-      tab_contents->profile(), NULL, MSG_ROUTING_NONE, NULL, NULL);
+      tab_contents->profile(), NULL, MSG_ROUTING_NONE, NULL);
   preview_contents_.reset(new TabContents(new_contents));
   AddPreviewUsageForHistogram(template_url_id_, PREVIEW_CREATED, group_);
   session_storage_namespace_ = GetSessionStorageNamespace(tab_contents);