ConsumerBase: make fence names meaningful

Change-Id: I3580120cb63c027c327e80ec70e68650b75395de
diff --git a/libs/gui/ConsumerBase.cpp b/libs/gui/ConsumerBase.cpp
index fd2d1cc..f5d6ff0 100644
--- a/libs/gui/ConsumerBase.cpp
+++ b/libs/gui/ConsumerBase.cpp
@@ -199,7 +199,7 @@
         mSlots[slot].mFence = fence;
     } else {
         sp<Fence> mergedFence = Fence::merge(
-                String8("ConsumerBase merged release"),
+                String8::format("%.28s:%d", mName.string(), slot),
                 mSlots[slot].mFence, fence);
         if (!mergedFence.get()) {
             CB_LOGE("failed to merge release fences");