Add MinidumpCrashpadInfoWriter and its test

minidump/minidump_string_writer_test_util.h

Index: minidump/minidump_string_writer_test_util.h
diff --git a/minidump/minidump_string_writer_test_util.h b/minidump/minidump_string_writer_test_util.h
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+++ b/minidump/minidump_string_writer_test_util.h
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+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <dbghelp.h>
+
+#include <string>
+
+#include "util/file/string_file_writer.h"
+
+namespace crashpad {
+namespace test {
+
+//! \brief Returns the contents of a MinidumpUTF8String.
+//!
+//! If \a rva points outside of the range of \a file_writer, or if any of the
+//! string data would lie outside of the range of \a file_writer, this function
+//! will fail.
+//!
+//! \param[in] file_writer A StringFileWriter into which MinidumpWritable
+//!     objects have been written.
+//! \param[in] rva An offset in \a file_writer at which to find the desired
+//!     string.
+//!
+//! \return On success, the string read from \a file_writer at offset \a rva. On
+//!     failure, returns an empty string, with a nonfatal assertion logged to
+//!     gtest.
+std::string MinidumpUTF8StringAtRVA(const StringFileWriter& file_writer,
+                                    RVA rva);
+
+}  // namespace test
+}  // namespace crashpad