Move OmahaQueryParams to a component and add a delegate interface.

components/omaha_query_params/omaha_query_params_delegate.h

+// Copyright 2014 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 COMPONENTS_OMAHA_QUERY_PARAMS_OMAHA_QUERY_PARAMS_DELEGATE_H_
+#define COMPONENTS_OMAHA_QUERY_PARAMS_OMAHA_QUERY_PARAMS_DELEGATE_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+
+namespace omaha_query_params {
+
+// Embedders can specify an OmahaQueryParamsDelegate to provide additional
+// custom parameters. If not specified (Set is never called), no additional
+// parameters are added.
+class OmahaQueryParamsDelegate {
+ public:
+  OmahaQueryParamsDelegate();
+  virtual ~OmahaQueryParamsDelegate();
+
+  // Returns additional parameters, if any. If there are any parameters, the
+  // string should begin with a & character.
+  virtual std::string GetExtraParams() = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(OmahaQueryParamsDelegate);
+};
+
+}  // namespace omaha_query_params
+
+#endif  // COMPONENTS_OMAHA_QUERY_PARAMS_OMAHA_QUERY_PARAMS_DELEGATE_H_