Make message_names.cc build 10-30x faster.

tools/ipc_fuzzer/message_lib/message_names.h

Index: tools/ipc_fuzzer/message_lib/message_names.h
diff --git a/tools/ipc_fuzzer/message_lib/message_names.h b/tools/ipc_fuzzer/message_lib/message_names.h
index 5a9e4427d5e7b585e98bc52cd3da0838ecaaa427..8b412d0081b64e33cfa92ce8f92d4df65da62783 100644
--- a/tools/ipc_fuzzer/message_lib/message_names.h
+++ b/tools/ipc_fuzzer/message_lib/message_names.h
@@ -7,8 +7,8 @@
 
 #include <stdint.h>
 
-#include <map>
 #include <string>
+#include <unordered_map>
 #include "base/logging.h"
 #include "base/macros.h"
 
@@ -46,8 +46,8 @@ class MessageNames {
   }
 
  private:
-  typedef std::map<uint32_t, std::string> TypeToNameMap;
-  typedef std::map<std::string, uint32_t> NameToTypeMap;
+  typedef std::unordered_map<uint32_t, std::string> TypeToNameMap;
+  typedef std::unordered_map<std::string, uint32_t> NameToTypeMap;
   TypeToNameMap name_map_;
   NameToTypeMap type_map_;