Check and canonicalize CSS selectors before registering PageStateMatchers.

chrome/renderer/extensions/css_native_handler.h

Index: chrome/renderer/extensions/css_native_handler.h
diff --git a/chrome/renderer/extensions/css_native_handler.h b/chrome/renderer/extensions/css_native_handler.h
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+++ b/chrome/renderer/extensions/css_native_handler.h
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+// Copyright 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 CHROME_RENDERER_EXTENSIONS_CSS_NATIVE_HANDLER_H_
+#define CHROME_RENDERER_EXTENSIONS_CSS_NATIVE_HANDLER_H_
+
+#include "chrome/renderer/extensions/object_backed_native_handler.h"
+
+namespace extensions {
+
+class CssNativeHandler : public ObjectBackedNativeHandler {
+ public:
+  explicit CssNativeHandler(ChromeV8Context* context);
+
+ private:
+  // Expects one string argument that's a comma-separated list of compound CSS
+  // selectors (http://dev.w3.org/csswg/selectors4/#compound), and returns its
+  // Blink-canonicalized form. If the selector is invalid, returns an empty
+  // string.
+  void CanonicalizeCompoundSelector(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_RENDERER_EXTENSIONS_CSS_NATIVE_HANDLER_H_