AU: Implement getting of tracks through GetTrack.

omaha_request_params.h

 // Copyright (c) 2010 The Chromium OS 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 CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_REQUEST_PARAMS_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_REQUEST_PARAMS_H__
 
 #include <string>
 
 #include <base/basictypes.h>
@@ skipping 62 matching lines @@
   // |in_app_version| or |in_update_url| prevents automatic detection
   // of the parameter. Returns true on success, false otherwise.
   bool Init(const std::string& in_app_version,
             const std::string& in_update_url);
 
   // Permanently changes the release track to |track|. Returns true on success,
   // false otherwise.
   bool SetTrack(const std::string& track);
   static bool SetDeviceTrack(const std::string& track);
 
+  // Returns the release track. On error, returns an empty string.
+  static std::string GetDeviceTrack();
+
   // For unit-tests.
   void set_root(const std::string& root) { root_ = root; }
 
   // Force build type for testing purposes.
   void SetBuildTypeOfficial(bool is_official);
 
  private:
   FRIEND_TEST(OmahaRequestDeviceParamsTest, IsValidTrackTest);
 
   // Use a validator that is a non-static member of this class so that its
@@ skipping 30 matching lines @@
   // Force build type for testing purposes.
   bool force_build_type_;
   bool forced_official_build_;
 
   DISALLOW_COPY_AND_ASSIGN(OmahaRequestDeviceParams);
 };
 
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_REQUEST_PARAMS_H__