Implement delete methods for the various CannedBrowsingDataHelpers.

chrome/browser/browsing_data/cookies_tree_model.cc

Index: chrome/browser/browsing_data/cookies_tree_model.cc
diff --git a/chrome/browser/browsing_data/cookies_tree_model.cc b/chrome/browser/browsing_data/cookies_tree_model.cc
index 51fe80d21f1044f5c709b8efc491db67aac535bc..a22068a1b4b01039d73130b845a0a0975ff7d51b 100644
--- a/chrome/browser/browsing_data/cookies_tree_model.cc
+++ b/chrome/browser/browsing_data/cookies_tree_model.cc
@@ -397,6 +397,10 @@ void CookieTreeSessionStorageNode::DeleteStoredObjects() {
   LocalDataContainer* container = GetLocalDataContainerForNode(this);
 
   if (container) {
+    // TODO(rsesek): There's no easy way to get the namespace_id for a session
+    // storage, nor is there an easy way to clear session storage just by
+    // origin. This is probably okay since session storage is not persistent.
+    // http://crbug.com/168996
     container->session_storage_info_list_.erase(session_storage_info_);
   }
 }