[Chromecast] Don't override RegisterCrashKeys() on Android.

chromecast/crash/cast_crash_keys.h

 // Copyright 2015 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 CHROMECAST_CRASH_CAST_CRASH_KEYS_H_
 #define CHROMECAST_CRASH_CAST_CRASH_KEYS_H_
 
 #include <stddef.h>
 
 #include "base/debug/crash_logging.h"
 
 namespace chromecast {
 namespace crash_keys {
 
-size_t RegisterCastCrashKeys();
+// TODO(slan|sanfin): Currently, the crash keys are unused on Cast. Without
+// calling base::debug::InitCrashKeys(), all calls to set crash key values are
+// no-ops.
+//
+// One problem with registering the crash keys here is that other modules have
+// their keys registered in chrome/common/crash_keys.cc, and if that file
+// changes without also updating our own registration function, we will
+// encounter crashes.
+//
+// crbug.com/598854 tracks an effort to allow componentizing crash key
+// definitions so we can remove this implicit dependency on //chrome.
 
 extern const char kCurrentApp[];
 extern const char kLastApp[];
 extern const char kPreviousApp[];
 
 }  // namespace chromecast
 }  // namespace crash_keys
 
 #endif  // CHROMECAST_CRASH_CAST_CRASH_KEYS_H_