Visit image roots for hprof

Bug: 19995360

(cherry picked from commit 0cab5e68f14ee403380664146db6dc7ddfc32064)

Change-Id: I17868bff2a701dc25291d41b9732c6b86f92be08
diff --git a/runtime/runtime.h b/runtime/runtime.h
index 085335f..64b7183 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -298,6 +298,10 @@
   void VisitRoots(RootCallback* visitor, void* arg, VisitRootFlags flags = kVisitRootFlagAllRoots)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
+  // Visit image roots, only used for hprof since the GC uses the image space mod union table
+  // instead.
+  void VisitImageRoots(RootCallback* visitor, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
   // Visit all of the roots we can do safely do concurrently.
   void VisitConcurrentRoots(RootCallback* visitor, void* arg,
                             VisitRootFlags flags = kVisitRootFlagAllRoots)