Added prerendering to omnibox.

chrome/browser/prerender/prerender_origin.h

+// Copyright (c) 2011 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_BROWSER_PRERENDER_PRERENDER_ORIGIN_H_
+#define CHROME_BROWSER_PRERENDER_PRERENDER_ORIGIN_H_
+
+namespace prerender {
+
+// Origin indicates what caused the prerender.
+// NOTE: New values need to be appended, since they are used in histograms.
+enum Origin {
+  ORIGIN_LINK_REL_PRERENDER = 0,
+  ORIGIN_PENDING_LINK_REL_PRERENDER = 1,
+  ORIGIN_OMNIBOX = 2,
+  ORIGIN_MAX
+};
+
+void RecordOrigin(Origin source);
+
+// Return a human-readable name for |origin|.
+const char* NameFromOrigin(Origin origin);
+
+}  // namespace prerender
+
+#endif  // CHROME_BROWSER_PRERENDER_PRERENDER_ORIGIN_H_