Add common code for extensions event filtering.

chrome/common/extensions/event_matcher.cc

Index: chrome/common/extensions/event_matcher.cc
diff --git a/chrome/common/extensions/event_matcher.cc b/chrome/common/extensions/event_matcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1f9e47481c9baac0e2c046fbdd3bd06df53ed6fa
--- /dev/null
+++ b/chrome/common/extensions/event_matcher.cc
@@ -0,0 +1,22 @@
+// 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.
+
+#include "chrome/common/extensions/event_matcher.h"
+#include "chrome/common/extensions/event_filtering_info.h"
+
+namespace extensions {
+
+EventMatcher::EventMatcher() {
+}
+
+EventMatcher::~EventMatcher() {
+}
+
+bool EventMatcher::MatchNonURLCriteria(
+    const EventFilteringInfo& event_info) const {
+  // There is currently no criteria apart from URL criteria.
+  return true;
+}
+
+}  // namespace extensions