Revert of [debugger api] remove legacy JSON debug protocol.

src/log.cc

Index: src/log.cc
diff --git a/src/log.cc b/src/log.cc
index ab4148c05d04337436dde4585bb3bf6e37dc3f99..0095cf43a7d5ddad1a38e4d37a899b7cae537fc9 100644
--- a/src/log.cc
+++ b/src/log.cc
@@ -1248,6 +1248,28 @@
   msg.WriteToLogFile();
 }
 
+
+void Logger::DebugTag(const char* call_site_tag) {
+  if (!log_->IsEnabled() || !FLAG_log) return;
+  Log::MessageBuilder msg(log_);
+  msg.Append("debug-tag,%s", call_site_tag);
+  msg.WriteToLogFile();
+}
+
+
+void Logger::DebugEvent(const char* event_type, Vector<uint16_t> parameter) {
+  if (!log_->IsEnabled() || !FLAG_log) return;
+  StringBuilder s(parameter.length() + 1);
+  for (int i = 0; i < parameter.length(); ++i) {
+    s.AddCharacter(static_cast<char>(parameter[i]));
+  }
+  char* parameter_string = s.Finalize();
+  Log::MessageBuilder msg(log_);
+  msg.Append("debug-queue-event,%s,%15.3f,%s", event_type,
+             base::OS::TimeCurrentMillis(), parameter_string);
+  DeleteArray(parameter_string);
+  msg.WriteToLogFile();
+}
 
 void Logger::RuntimeCallTimerEvent() {
   RuntimeCallStats* stats = isolate_->counters()->runtime_call_stats();