Refactor trace_event_impl's SetEnabled to use TraceOptions. Propagate this through the whole stack.

components/tracing/child_trace_message_filter.h

Index: components/tracing/child_trace_message_filter.h
diff --git a/components/tracing/child_trace_message_filter.h b/components/tracing/child_trace_message_filter.h
index 5bd993e80e489947f2038b271d1ebda46638df84..596e73840a12ad23e4db8d0fa88db54f40e01193 100644
--- a/components/tracing/child_trace_message_filter.h
+++ b/components/tracing/child_trace_message_filter.h
@@ -32,11 +32,11 @@ class ChildTraceMessageFilter : public IPC::MessageFilter {
   // Message handlers.
   void OnBeginTracing(const std::string& category_filter_str,
                       base::TimeTicks browser_time,
-                      int options);
+                      const std::string& options);
   void OnEndTracing();
   void OnEnableMonitoring(const std::string& category_filter_str,
                           base::TimeTicks browser_time,
-                          int options);
+                          const std::string& options);
   void OnDisableMonitoring();
   void OnCaptureMonitoringSnapshot();
   void OnGetTraceBufferPercentFull();