More of the concurrent copying collector.

Bug: 12687968
Change-Id: I62f70274d47df6d6cab714df95c518b750ce3105
diff --git a/runtime/thread_list.h b/runtime/thread_list.h
index 6751bf5..d18315a 100644
--- a/runtime/thread_list.h
+++ b/runtime/thread_list.h
@@ -27,6 +27,11 @@
 #include <list>
 
 namespace art {
+namespace gc {
+  namespace collector {
+    class GarbageCollector;
+  }  // namespac collector
+}  // namespace gc
 class Closure;
 class Thread;
 class TimingLogger;
@@ -95,6 +100,14 @@
   LOCKS_EXCLUDED(Locks::thread_list_lock_,
                  Locks::thread_suspend_count_lock_);
 
+  // Flip thread roots from from-space refs to to-space refs. Used by
+  // the concurrent copying collector.
+  size_t FlipThreadRoots(Closure* thread_flip_visitor, Closure* flip_callback,
+                         gc::collector::GarbageCollector* collector)
+      LOCKS_EXCLUDED(Locks::mutator_lock_,
+                     Locks::thread_list_lock_,
+                     Locks::thread_suspend_count_lock_);
+
   // Suspends all threads
   void SuspendAllForDebugger()
       LOCKS_EXCLUDED(Locks::mutator_lock_,