Remove knowledge of Chrome-specific SyncableService classes from WebDataService.

chrome/browser/api/webdata/web_data_service_base.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_API_WEBDATA_WEB_DATA_SERVICE_BASE_H_
 #define CHROME_BROWSER_API_WEBDATA_WEB_DATA_SERVICE_BASE_H_
 
 #include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/supports_user_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_source.h"
 #include "sql/init_status.h"
 
 class WebDatabase;
 class WebDatabaseService;
 
 namespace base {
 class Thread;
 }
@@ skipping 41 matching lines @@
 
   // Returns true if the database load has completetd successfully, and
   // ShutdownOnUIThread has not yet been called.
   virtual bool IsDatabaseLoaded();
 
   // Returns a pointer to the DB (used by SyncableServices). May return NULL if
   // the database is not loaded or otherwise unavailable. Must be called on
   // DBThread.
   virtual WebDatabase* GetDatabase();
 
+  // Returns a SupportsUserData objects that may be used to store data
+  // owned by the DB thread on this object. Should be called only from
+  // the DB thread, and will be destroyed on the DB thread soon after
+  // |ShutdownOnUIThread()| is called.
+  base::SupportsUserData* GetDBUserData();
+
  protected:
   virtual ~WebDataServiceBase();
+  virtual void ShutdownOnDBThread();
 
   // Our database service.
   scoped_ptr<WebDatabaseService> wdbs_;
 
   // True if we've received a notification that the WebDatabase has loaded.
   bool db_loaded_;
 
  private:
   friend struct content::BrowserThread::DeleteOnThread<
       content::BrowserThread::UI>;
   friend class base::DeleteHelper<WebDataServiceBase>;
 
   ProfileErrorCallback profile_error_callback_;
 
+  // This makes the destructor public, and thus allows us to aggregate
+  // SupportsUserData. It is private by default to prevent incorrect
+  // usage in class hierarchies where it is inherited by
+  // reference-counted objects.
+  class SupportsUserDataAggregatable : public base::SupportsUserData {
+   public:
+    SupportsUserDataAggregatable() {}
+    virtual ~SupportsUserDataAggregatable() {}
+   private:
+    DISALLOW_COPY_AND_ASSIGN(SupportsUserDataAggregatable);
+  };
+
+  // Storage for user data to be accessed only on the DB thread. May
+  // be used e.g. for SyncableService subclasses that need to be owned
+  // by this object. Is created on first call to |GetDBUserData()|.
+  scoped_ptr<SupportsUserDataAggregatable> db_thread_user_data_;
+
   void DBInitFailed(sql::InitStatus sql_status);
   void NotifyDatabaseLoadedOnUIThread();
   void DatabaseInitOnDB(sql::InitStatus status);
 };
 
 #endif  // CHROME_BROWSER_API_WEBDATA_WEB_DATA_SERVICE_BASE_H_