Implemented proper support for checking schemes and requested resource types.

chrome/browser/extensions/api/declarative_webrequest/webrequest_helpers.cc

+// 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_webrequest/webrequest_helpers.h"
+
+#include "base/values.h"
+
+namespace extensions {
+namespace declarative_webrequest_helpers {
+
+// Converts a ValueList |value| of strings into a vector. Returns true if
+// successful.
+bool GetAsStringVector(const base::Value* value,
+                       std::vector<std::string>* out) {
+  const ListValue* value_as_list = 0;
+  if (!value->GetAsList(&value_as_list))
+    return false;
+
+  size_t number_types = value_as_list->GetSize();
+  for (size_t i = 0; i < number_types; ++i) {
+    std::string item;
+    if (!value_as_list->GetString(i, &item))
+      return false;
+    out->push_back(item);
+  }
+  return true;
+}
+
+}  // namespace declarative_webrequest_helpers
+}  // namespace extensions