Factor out logic to find chrome.exe from Omaha client state.

chrome/installer/launcher_support/chrome_launcher_support.h

+// 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.
+
+#ifndef CHROME_INSTALLER_LAUNCHER_SUPPORT_CHROME_LAUNCHER_SUPPORT_H_
+#define CHROME_INSTALLER_LAUNCHER_SUPPORT_CHROME_LAUNCHER_SUPPORT_H_
+#pragma once
+
+class FilePath;
+
+namespace chrome_launcher_support {
+
+enum InstallationLevel {
+  USER_LEVEL_INSTALLATION,
+  SYSTEM_LEVEL_INSTALLATION
+};
+
+// Returns the path to an installed chrome.exe, or an empty path. Prefers a
+// system-level installation to a user-level installation. Uses Omaha client
+// state to identify Chrome installations, but will fall back to an unregistered
+// installation in DIR_PROGRAM_FILES (according to PathService) as well.
+FilePath GetAnyChromePath();
+
+// Returns the path to an installed chrome.exe at the specified level, if it can
+// be found via Omaha client state.
+FilePath GetChromePathForInstallationLevel(InstallationLevel level);
+
+}  // namespace chrome_launcher_support
+
+#endif  // CHROME_INSTALLER_LAUNCHER_SUPPORT_CHROME_LAUNCHER_SUPPORT_H_