Add an abstraction over a compiled code.

That's just step 1, moving code-related functions of ArtMethod to
another class. That class is only a wrapper on an ArtMethod, but will
be changed to be a wrapper around compiled code.

Change-Id: I6f35fc06d37220558dff61691e51ae20066b0dd6
diff --git a/runtime/instrumentation.cc b/runtime/instrumentation.cc
index deada4c..5ff016a 100644
--- a/runtime/instrumentation.cc
+++ b/runtime/instrumentation.cc
@@ -19,6 +19,7 @@
 #include <sstream>
 
 #include "arch/context.h"
+#include "art_code.h"
 #include "art_method-inl.h"
 #include "atomic.h"
 #include "class_linker.h"
@@ -251,7 +252,7 @@
         instrumentation_stack_->insert(it, instrumentation_frame);
         SetReturnPc(instrumentation_exit_pc_);
       }
-      dex_pcs_.push_back(m->ToDexPc(last_return_pc_));
+      dex_pcs_.push_back(GetCurrentCode().ToDexPc(last_return_pc_));
       last_return_pc_ = return_pc;
       ++instrumentation_stack_depth_;
       return true;  // Continue.