[Extensions] Fix thread-safety bug in PermissionsData

extensions/common/permissions/permissions_data.h

 // Copyright (c) 2013 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 EXTENSIONS_COMMON_PERMISSIONS_PERMISSIONS_DATA_H_
 #define EXTENSIONS_COMMON_PERMISSIONS_PERMISSIONS_DATA_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 183 matching lines @@
                                     int tab_id,
                                     int process_id,
                                     std::string* error) const;
 
   // Returns true if extension is allowed to obtain the contents of a page as
   // an image. Since a page may contain sensitive information, this is
   // restricted to the extension's host permissions as well as the extension
   // page itself.
   bool CanCaptureVisiblePage(int tab_id, std::string* error) const;
 
-  const scoped_refptr<const PermissionSet>& active_permissions() const {
+  // Returns the tab permissions map.
+  TabPermissionsMap CopyTabSpecificPermissionsMap() const;
+
+  scoped_refptr<const PermissionSet> active_permissions() const {
     // We lock so that we can't also be setting the permissions while returning.
     base::AutoLock auto_lock(runtime_lock_);
     return active_permissions_unsafe_;
   }
 
-  const scoped_refptr<const PermissionSet>& withheld_permissions() const {
+  scoped_refptr<const PermissionSet> withheld_permissions() const {
     // We lock so that we can't also be setting the permissions while returning.
     base::AutoLock auto_lock(runtime_lock_);
     return withheld_permissions_unsafe_;
   }
 
-  const TabPermissionsMap& tab_specific_permissions() const {
-    // We lock so that we can't also be setting the permissions while returning.
-    base::AutoLock auto_lock(runtime_lock_);
-    return tab_specific_permissions_;
-  }
-
 #if defined(UNIT_TEST)
   scoped_refptr<const PermissionSet> GetTabSpecificPermissionsForTesting(
       int tab_id) const {
     return GetTabSpecificPermissions(tab_id);
   }
 #endif
 
  private:
   // Gets the tab-specific host permissions of |tab_id|, or NULL if there
   // aren't any.
@@ skipping 42 matching lines @@
   mutable scoped_refptr<const PermissionSet> withheld_permissions_unsafe_;
 
   mutable TabPermissionsMap tab_specific_permissions_;
 
   DISALLOW_COPY_AND_ASSIGN(PermissionsData);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_PERMISSIONS_PERMISSIONS_DATA_H_