<webview>: Add support for filtering extension events by instanceId.

extensions/common/event_matcher.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 EXTENSIONS_COMMON_EVENT_MATCHER_H_
 #define EXTENSIONS_COMMON_EVENT_MATCHER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
 
@@ skipping 12 matching lines @@
 
   // Returns true if |event_info| satisfies this matcher's criteria, not taking
   // into consideration any URL criteria.
   bool MatchNonURLCriteria(const EventFilteringInfo& event_info) const;
 
   int GetURLFilterCount() const;
   bool GetURLFilter(int i, base::DictionaryValue** url_filter_out);
 
   int HasURLFilters() const;
 
+  int GetInstanceID() const;
+
   base::DictionaryValue* value() const {
     return filter_.get();
   }
 
  private:
   // Contains a dictionary that corresponds to a single event filter, eg:
   //
   // {url: [{hostSuffix: 'google.com'}]}
   //
   // The valid filter keys are event-specific.
   scoped_ptr<base::DictionaryValue> filter_;
 
   DISALLOW_COPY_AND_ASSIGN(EventMatcher);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_EVENT_MATCHER_H_