system_wrappers: Fix include header guards.

webrtc/system_wrappers/include/field_trial.h

 //
 // Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the LICENSE file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS.  All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 //
 
-#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_FIELD_TRIAL_H_
-#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_FIELD_TRIAL_H_
+#ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_FIELD_TRIAL_H_
+#define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_FIELD_TRIAL_H_
 
 #include <string>
 
 // Field trials allow webrtc clients (such as Chrome) to turn on feature code
 // in binaries out in the field and gather information with that.
 //
 // WebRTC clients MUST provide an implementation of:
 //
 //   std::string webrtc::field_trial::FindFullName(const std::string& trial).
 //
@@ skipping 35 matching lines @@
 
 // Returns the group name chosen for the named trial, or the empty string
 // if the trial does not exists.
 //
 // Note: To keep things tidy append all the trial names with WebRTC.
 std::string FindFullName(const std::string& name);
 
 }  // namespace field_trial
 }  // namespace webrtc
 
-#endif  // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_FIELD_TRIAL_H_
+#endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_FIELD_TRIAL_H_