split surface management from surface's buffers management

Change-Id: If3c5655d1231f8f0c49ba68f972b1b20c93b3f87
diff --git a/include/surfaceflinger/ISurfaceComposerClient.h b/include/surfaceflinger/ISurfaceComposerClient.h
index b2a4766..a1e9e04 100644
--- a/include/surfaceflinger/ISurfaceComposerClient.h
+++ b/include/surfaceflinger/ISurfaceComposerClient.h
@@ -58,6 +58,7 @@
     };
 
     virtual sp<IMemoryHeap> getControlBlock() const = 0;
+    virtual ssize_t getTokenForSurface(const sp<ISurface>& sur) const = 0;
 
     /*
      * Requires ACCESS_SURFACE_FLINGER permission