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

mojo/public/cpp/system/tests/data_pipe_unittest.cc

 // Copyright 2016 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 file tests the C++ wrappers in mojo/public/cpp/system/data_pipe.h.
 
 #include "mojo/public/cpp/system/data_pipe.h"
 
+#include "gtest/gtest.h"
 #include "mojo/public/cpp/system/handle.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "mojo/public/cpp/system/wait.h"
-#include "testing/gtest/include/gtest/gtest.h"
 
 namespace mojo {
 namespace {
 
 TEST(DataPipe, Basic) {
   // Cursory compilation tests of |MakeScopedHandle()| with data pipe handles.
   EXPECT_FALSE(MakeScopedHandle(DataPipeProducerHandle()).is_valid());
   EXPECT_FALSE(MakeScopedHandle(DataPipeConsumerHandle()).is_valid());
 
   ScopedDataPipeProducerHandle ph;
@@ skipping 89 matching lines @@
   // Close the producer.
   ph.reset();
 
   // Waiting for "read" should now fail.
   EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION,
             Wait(ch.get(), MOJO_HANDLE_SIGNAL_READ_THRESHOLD, 1000, nullptr));
 }
 
 }  // namespace mojo
 }  // namespace