Define crash keys in the directory hierarchy where they are used.

media/base/crash_keys.h

+// 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.
+
+#ifndef MEDIA_BASE_CRASH_KEYS_H_
+#define MEDIA_BASE_CRASH_KEYS_H_
+
+#include <vector>
+
+#include "base/debug/crash_logging.h"
+#include "build/build_config.h"
+#include "media/base/media_export.h"
+
+namespace crash_keys {
+
+// Crash keys
+#if defined(OS_WIN)
+extern const char kHungAudioThreadDetails[];
+#endif
+extern const char kZeroEncodeDetails[];
+
+// Appends crash keys used under //media to |keys|.
+MEDIA_EXPORT void AppendMediaCrashKeys(
+    std::vector<base::debug::CrashKey>* keys);
+
+}  // namespace crash_keys
+
+#endif  // MEDIA_BASE_CRASH_KEYS_H_