mojo/public: Include gtest.h as "gtest/gtest.h", instead of via "absolute" path.

mojo/public/c/tests/system/message_pipe_perftest.cc

 // Copyright 2013 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.
 
 // This tests the performance of message pipes via the C API.
 
 #include <mojo/system/message_pipe.h>
 
 #include <assert.h>
 #include <mojo/macros.h>
 #include <mojo/result.h>
 #include <mojo/system/handle.h>
 #include <mojo/system/time.h>
 #include <mojo/system/wait.h>
 #include <stdint.h>
 #include <stdio.h>
 
 #include <thread>
 
+#include "gtest/gtest.h"
 #include "mojo/public/c/tests/system/perftest_utils.h"
 #include "mojo/public/cpp/test_support/test_support.h"
-#include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 TEST(MessagePipePerftest, CreateAndClose) {
   mojo::test::IterateAndReportPerf("MessagePipe_CreateAndClose", nullptr, []() {
     MojoHandle h0;
     MojoHandle h1;
     MojoResult result = MojoCreateMessagePipe(nullptr, &h0, &h1);
     MOJO_ALLOW_UNUSED_LOCAL(result);
     assert(result == MOJO_RESULT_OK);
@@ skipping 196 matching lines @@
   DoMessagePipeThreadedTest(1u, 1u, 1000u);
   DoMessagePipeThreadedTest(1u, 1u, 10000u);
 
   DoMessagePipeThreadedTest(3u, 3u, 10u);
   // 100 was done above.
   DoMessagePipeThreadedTest(3u, 3u, 1000u);
   DoMessagePipeThreadedTest(3u, 3u, 10000u);
 }
 
 }  // namespace