[optimizing] Add memory barriers in constructors when needed

If a class has final fields we must add a memory barrier before
returning from constructor. This makes sure the fields are visible to
other threads.

Bug: 19851497
Change-Id: If8c485092fc512efb9636cd568cb0543fb27688e
diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index 4c28378..ca9cbc3 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -192,6 +192,10 @@
     output_ << " " << phi->GetRegNumber();
   }
 
+  void VisitMemoryBarrier(HMemoryBarrier* barrier) OVERRIDE {
+    output_ << " " << barrier->GetBarrierKind();
+  }
+
   bool IsPass(const char* name) {
     return strcmp(pass_name_, name) == 0;
   }