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

mojo/public/c/tests/bindings/message_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.
 
 #include <mojo/bindings/message.h>
 
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
+#include "gtest/gtest.h"
 #include "mojo/public/cpp/bindings/tests/validation_test_input_parser.h"
 #include "mojo/public/cpp/system/macros.h"
-#include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 TEST(MessageValidationTest, InvalidMessageHeader) {
   struct TestCase {
     const char* test_case;
     uint32_t size;
     const char* name;
     MojomValidationResult validation_result;
   };
@@ skipping 93 matching lines @@
     ASSERT_TRUE(mojo::test::ParseValidationTestInput(
         cases[i].test_case, &data, &num_handles, &parser_error_message))
         << parser_error_message << " case " << i;
     EXPECT_EQ(MOJOM_VALIDATION_ERROR_NONE,
               MojomMessage_ValidateHeader(data.data(), cases[i].size))
         << " case " << i;
   }
 }
 
 }  // namespace