ART: Move trace options to a struct

Bundles the different options and moves them to a struct in the
implementation file. Will allow for easier change for streaming.

Change-Id: I486e0942614e714964eb233e2d6b4e3e12aa704f
diff --git a/runtime/runtime.h b/runtime/runtime.h
index 64b7183..68458ae 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -81,6 +81,7 @@
 class SuspensionHandler;
 class ThreadList;
 class Trace;
+struct TraceConfig;
 class Transaction;
 
 typedef std::vector<std::pair<std::string, const void*>> RuntimeOptions;
@@ -675,9 +676,8 @@
   ProfilerOptions profiler_options_;
   bool profiler_started_;
 
-  bool method_trace_;
-  std::string method_trace_file_;
-  size_t method_trace_file_size_;
+  std::unique_ptr<TraceConfig> trace_config_;
+
   instrumentation::Instrumentation instrumentation_;
 
   jobject main_thread_group_;