Makes the BattOrAgent asynchronous

tools/battor_agent/battor_agent.cc

Index: tools/battor_agent/battor_agent.cc
diff --git a/tools/battor_agent/battor_agent.cc b/tools/battor_agent/battor_agent.cc
index 744c61b6db5ae1430260be1880ac18bcc6f0d3a5..e1751d4462074584add48006c64555444f603745 100644
--- a/tools/battor_agent/battor_agent.cc
+++ b/tools/battor_agent/battor_agent.cc
@@ -6,6 +6,9 @@
 
 #include <iostream>
 
+#include "base/callback.h"
+#include "base/memory/scoped_ptr.h"
+
 namespace battor {
 
 BattOrAgent::BattOrAgent(const std::string& path) : path_(path) {
@@ -20,12 +23,17 @@ void BattOrAgent::StartTracing() {
   // TODO: Tell the BattOr to start tracing.
 }
 
-void BattOrAgent::StopTracing(std::string* out_trace) {
+void BattOrAgent::StopTracing(std::string* trace_output,
+                              const base::Closure& callback) {
   // TODO: Tell the BattOr to stop tracing.
+  *trace_output = "battor trace output";
+  callback.Run();
 }
 
-void BattOrAgent::RecordClockSyncMarker(const std::string& marker) {
+void BattOrAgent::RecordClockSyncMarker(const std::string& marker,
+                                        const base::Closure& callback) {
   // TODO: Tell the BattOr to record the specified clock sync marker.
+  callback.Run();
 }
 
 void BattOrAgent::IssueClockSyncMarker() {