Count number of origins with data affected by clearing "cookies and site data".

content/browser/dom_storage/dom_storage_context_impl.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 "content/browser/dom_storage/dom_storage_context_impl.h"
 
 #include <inttypes.h>
 #include <stddef.h>
 #include <stdlib.h>
 
@@ skipping 238 matching lines @@
       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_t namespace_id = AllocateSessionId();
     CreateSessionNamespace(namespace_id, usage_info.persistent_namespace_id);
     dom_storage_namespace = GetStorageNamespace(namespace_id);
   }
   dom_storage_namespace->DeleteSessionStorageOrigin(usage_info.origin);
+  // TODO? This removes remaining traces of deleted sessions but I don't know if
+  // it could interfere with whatever happens with this clear event below?
+  /*if (session_storage_database_.get()) {

[msramek, 2017/01/09 12:54:44]

Since you already know how to solve it, just need a confirmation from the code
owners that it's the right thing, I'd suggest extracting this to a separate CL.

[dullweber, 2017/01/09 16:05:46]

I created https://codereview.chromium.org/2622603002

+    task_runner_->PostShutdownBlockingTask(
+        FROM_HERE, DOMStorageTaskRunner::COMMIT_SEQUENCE,
+        base::Bind(base::IgnoreResult(&SessionStorageDatabase::DeleteArea),
+                   session_storage_database_,
+                   usage_info.persistent_namespace_id, 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::Flush() {
   for (auto& entry : namespaces_)
@@ skipping 362 matching lines @@
   if (!deletable_persistent_namespace_ids_.empty()) {
     task_runner_->PostDelayedTask(
         FROM_HERE, base::Bind(
             &DOMStorageContextImpl::DeleteNextUnusedNamespace,
             this),
         base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
   }
 }
 
 }  // namespace content