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

mojo/public/c/tests/system/wait_set_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 wait set API (the functions declared in
 // mojo/public/c/include/mojo/system/wait_set.h).
 
 #include <mojo/system/wait_set.h>
 
 #include <mojo/result.h>
 #include <mojo/system/handle.h>
 #include <mojo/system/message_pipe.h>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "gtest/gtest.h"
 
 namespace {
 
 const MojoHandleRights kDefaultWaitSetHandleRights =
     MOJO_HANDLE_RIGHT_READ | MOJO_HANDLE_RIGHT_WRITE |
     MOJO_HANDLE_RIGHT_GET_OPTIONS | MOJO_HANDLE_RIGHT_SET_OPTIONS;
 
 TEST(WaitSetTest, InvalidHandle) {
   EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
             MojoWaitSetAdd(MOJO_HANDLE_INVALID, MOJO_HANDLE_INVALID,
@@ skipping 357 matching lines @@
         MOJO_RESULT_CANCELLED, MojoHandleSignalsState()));
   }
 
   EXPECT_EQ(MOJO_RESULT_OK, MojoClose(h));
   EXPECT_EQ(MOJO_RESULT_OK, MojoClose(mph1));
 }
 
 // TODO(vtl): Add threaded tests, especially those that actually ... wait.
 
 }  // namespace