Revert of Remove the rtc_relative_path GYP variable and similar defines

webrtc/base/gunit.h

 /*
  *  Copyright 2004 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_BASE_GUNIT_H_
 #define WEBRTC_BASE_GUNIT_H_
 
 #include "webrtc/base/logging.h"
 #include "webrtc/base/thread.h"
+#if defined(GTEST_RELATIVE_PATH)
 #include "testing/gtest/include/gtest/gtest.h"
+#else
+#include "testing/base/public/gunit.h"
+#endif
 
 // Wait until "ex" is true, or "timeout" expires.
 #define WAIT(ex, timeout)                                                     \
   for (uint32_t start = rtc::Time(); !(ex) && rtc::Time() < start + timeout;) \
     rtc::Thread::Current()->ProcessMessages(1);
 
 // This returns the result of the test in res, so that we don't re-evaluate
 // the expression in the XXXX_WAIT macros below, since that causes problems
 // when the expression is only true the first time you check it.
 #define WAIT_(ex, timeout, res)                     \
@@ skipping 47 matching lines @@
     } \
     LOG(LS_WARNING) << "Expression " << #ex << " still not true after " << \
         timeout << "ms; waiting an additional " << margin << "ms"; \
     WAIT_(ex, margin, res); \
     if (!res) { \
       EXPECT_TRUE(ex); \
     } \
   } while (0)
 
 #endif  // WEBRTC_BASE_GUNIT_H_