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

mojo/public/cpp/system/tests/handle_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/handle.h.
 
 #include "mojo/public/cpp/system/handle.h"
 
 #include <map>
 #include <utility>
 
+#include "gtest/gtest.h"
 #include "mojo/public/cpp/system/buffer.h"
 #include "mojo/public/cpp/system/macros.h"
-#include "testing/gtest/include/gtest/gtest.h"
 
 namespace mojo {
 namespace {
 
 // Basic |Handle| tests.
 TEST(HandleTest, Handle) {
   EXPECT_EQ(MOJO_HANDLE_INVALID, kInvalidHandleValue);
 
   Handle h0;
   EXPECT_EQ(kInvalidHandleValue, h0.value());
@@ skipping 182 matching lines @@
             GetRights(buffer3.get()) & (kDuplicate | kTransfer | kGetOptions));
   EXPECT_EQ(kDuplicate,
             GetRights(buffer2.get()) & (kDuplicate | kTransfer | kGetOptions));
 }
 
 // TODO(vtl): Test |CloseRaw()|.
 // TODO(vtl): Test |reset()| more thoroughly?
 
 }  // namespace mojo
 }  // namespace