Implement declarativeContent API.

chrome/browser/extensions/api/declarative_content/content_constants.cc

Index: chrome/browser/extensions/api/declarative_content/content_constants.cc
diff --git a/chrome/browser/extensions/api/declarative_content/content_constants.cc b/chrome/browser/extensions/api/declarative_content/content_constants.cc
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+++ b/chrome/browser/extensions/api/declarative_content/content_constants.cc
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+// 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/browser/extensions/api/declarative_content/content_constants.h"
+
+namespace extensions {
+namespace declarative_content_constants {
+
+// Signals to which ContentRulesRegistries are registered.
+const char kOnPageChanged[] = "declarativeContent.onPageChanged";
+
+// Keys of dictionaries.
+const char kCss[] = "css";
+const char kInstanceType[] = "instanceType";
+const char kTopUrl[] = "top_url";
+
+// Values of dictionaries, in particular instance types
+const char kPageStateMatcherType[] = "declarativeContent.PageStateMatcher";
+const char kShowPageAction[] = "declarativeContent.ShowPageAction";
+
+}  // namespace declarative_content_constants
+}  // namespace extensions