DM: also run benches once.

dm/DMTask.h

Index: dm/DMTask.h
diff --git a/dm/DMTask.h b/dm/DMTask.h
index 638a939304dd5dea8b36d6f4bb27d5869bbdffbf..e8598df85e00ee6001b3f2571f356a4ae91d7daa 100644
--- a/dm/DMTask.h
+++ b/dm/DMTask.h
@@ -2,6 +2,7 @@
 #define DMTask_DEFINED
 
 #include "DMReporter.h"
+#include "GrContextFactory.h"
 #include "SkRunnable.h"
 #include "SkThreadPool.h"
 
@@ -36,6 +37,9 @@ protected:
     void spawnChild(Task* task);
     void fail(const char* msg = NULL);
 
+    // This can only be safely called from a GPU task's draw() method.
+    GrContextFactory* getGrContextFactory() const;
+
 private:
     // Both unowned.
     Reporter* fReporter;