ART: Make RuntimeCallbacks unique_ptr

Reduce the transitive closure of headers on runtime.h

Test: m
Change-Id: Ib5a3632c28b08bf07773f217a7ad711c1f12af6b
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 92d1554..14918df 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -96,6 +96,7 @@
 #include "object_lock.h"
 #include "os.h"
 #include "runtime.h"
+#include "runtime_callbacks.h"
 #include "ScopedLocalRef.h"
 #include "scoped_thread_state_change-inl.h"
 #include "thread-inl.h"
@@ -2681,7 +2682,7 @@
 
   // At this point the class is loaded. Publish a ClassLoad even.
   // Note: this may be a temporary class. It is a listener's responsibility to handle this.
-  Runtime::Current()->GetRuntimeCallbacks().ClassLoad(klass);
+  Runtime::Current()->GetRuntimeCallbacks()->ClassLoad(klass);
 
   // Link the class (if necessary)
   CHECK(!klass->IsResolved());
@@ -2723,7 +2724,7 @@
    * The class has been prepared and resolved but possibly not yet verified
    * at this point.
    */
-  Runtime::Current()->GetRuntimeCallbacks().ClassPrepare(klass, h_new_class);
+  Runtime::Current()->GetRuntimeCallbacks()->ClassPrepare(klass, h_new_class);
 
   // Notify native debugger of the new class and its layout.
   jit::Jit::NewTypeLoadedIfUsingJit(h_new_class.Get());