Propagate 'this_object' for method unwind event.

Propagates the 'this_object' to InstrumentationListener::MethodUnwind callback.

Change-Id: I12561f1a611b8399b94e669f9b8a6eaaf1a58631
diff --git a/runtime/trace.cc b/runtime/trace.cc
index ec95a87..da2c80a 100644
--- a/runtime/trace.cc
+++ b/runtime/trace.cc
@@ -570,7 +570,8 @@
                       thread_clock_diff, wall_clock_diff);
 }
 
-void Trace::MethodUnwind(Thread* thread, const mirror::ArtMethod* method, uint32_t dex_pc) {
+void Trace::MethodUnwind(Thread* thread, mirror::Object* this_object,
+                         const mirror::ArtMethod* method, uint32_t dex_pc) {
   uint32_t thread_clock_diff = 0;
   uint32_t wall_clock_diff = 0;
   ReadClocks(thread, &thread_clock_diff, &wall_clock_diff);