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

extensions/common/event_filtering_info.h

Index: extensions/common/event_filtering_info.h
diff --git a/extensions/common/event_filtering_info.h b/extensions/common/event_filtering_info.h
index 2fee9c15db48293caac8052881b446cf89e8c354..a4895864d78cabbc8c080599500d3f4dff16db3a 100644
--- a/extensions/common/event_filtering_info.h
+++ b/extensions/common/event_filtering_info.h
@@ -27,11 +27,14 @@ class EventFilteringInfo {
   EventFilteringInfo();
   ~EventFilteringInfo();
   void SetURL(const GURL& url);
+  void SetInstanceID(int instance_id);
 
   bool has_url() const { return has_url_; }
   const GURL& url() const { return url_; }
 
-  std::string AsJSONString() const;
+  bool has_instance_id() const { return has_instance_id_; }
+  int instance_id() const { return instance_id_; }
+
   scoped_ptr<base::Value> AsValue() const;
   bool IsEmpty() const;
 
@@ -39,6 +42,9 @@ class EventFilteringInfo {
   bool has_url_;
   GURL url_;
 
+  bool has_instance_id_;
+  int instance_id_;
+
   // Allow implicit copy and assignment.
 };