Extension activity log database refactoring (step 1)

chrome/browser/extensions/activity_log/activity_log.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_ACTIVITY_LOG_H_
 #define CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_ACTIVITY_LOG_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 167 matching lines @@
 
   // At the moment, ActivityLog will use only one policy for summarization.
   // These methods are used to choose and set the most appropriate policy.
   void ChooseDefaultPolicy();
   void SetDefaultPolicy(ActivityLogPolicy::PolicyType policy_type);
 
   typedef ObserverListThreadSafe<Observer> ObserverList;
   scoped_refptr<ObserverList> observers_;
 
   // The policy object takes care of data summarization, compression, and
-  // logging
+  // logging.  The policy object is owned by the ActivityLog, but this cannot
+  // be a scoped_ptr since some cleanup work must happen on the database
+  // thread.  Calling policy_->Close() will free the object; see the comments
+  // on the ActivityDatabase class for full details.
   extensions::ActivityLogPolicy* policy_;
 
   // TODO(dbabic,felt) change this into a list of policy types later.
   ActivityLogPolicy::PolicyType policy_type_;
 
   Profile* profile_;
   bool enabled_;  // Whether logging is currently enabled.
   bool initialized_;  // Whether Init() has already been called.
   bool policy_chosen_;  // Whether we've already set the default policy.
   // testing_mode_ controls whether to log API call arguments. By default, we
@@ skipping 36 matching lines @@
   virtual content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(ActivityLogFactory);
 };
 
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_ACTIVITY_LOG_H_