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

chromecast/crash/cast_crash_keys.h

Index: chromecast/crash/cast_crash_keys.h
diff --git a/chromecast/crash/cast_crash_keys.h b/chromecast/crash/cast_crash_keys.h
index 13063846f9cce70121ad3f6a991ad8dcc5824d77..a8f8299daf7a67ec6cc3f2ecdfa2305a8b070ae0 100644
--- a/chromecast/crash/cast_crash_keys.h
+++ b/chromecast/crash/cast_crash_keys.h
@@ -12,7 +12,17 @@
 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[];