Use a class instead of several separate globals in crash_logging.cc.

base/debug/crash_logging.h

Index: base/debug/crash_logging.h
diff --git a/base/debug/crash_logging.h b/base/debug/crash_logging.h
index 90e6687bec8cdfd50fd629e0fe9e06996c05f6a4..47d19320321e4c408c3f2df48cf39bb3bcc946ce 100644
--- a/base/debug/crash_logging.h
+++ b/base/debug/crash_logging.h
@@ -95,9 +95,6 @@ BASE_EXPORT std::vector<std::string> ChunkCrashKeyValue(
     const base::StringPiece& value,
     size_t chunk_max_length);
 
-// Resets the crash key system so it can be reinitialized. For testing only.
-BASE_EXPORT void ResetCrashLoggingForTesting();
-
 }  // namespace debug
 }  // namespace base