Add a WAIT_FOR_GPU_COMPLETION option

Change-Id: I18d526120651676109200bfd5da87cafcd7e3d13
diff --git a/libs/hwui/renderthread/EglManager.h b/libs/hwui/renderthread/EglManager.h
index e12db3a..b1a18a9 100644
--- a/libs/hwui/renderthread/EglManager.h
+++ b/libs/hwui/renderthread/EglManager.h
@@ -55,6 +55,8 @@
 
     void setTextureAtlas(const sp<GraphicBuffer>& buffer, int64_t* map, size_t mapSize);
 
+    void fence();
+
 private:
     friend class RenderThread;