improve hwc dumpsys

we now log the buffer's format

Change-Id: I9d3ad8018e884240a153de3baefb6331cb014d0f
diff --git a/services/surfaceflinger/LayerBase.h b/services/surfaceflinger/LayerBase.h
index ee50428..a14b397 100644
--- a/services/surfaceflinger/LayerBase.h
+++ b/services/surfaceflinger/LayerBase.h
@@ -46,6 +46,7 @@
 class DisplayHardware;
 class GraphicBuffer;
 class GraphicPlane;
+class Layer;
 class LayerBaseClient;
 class SurfaceFlinger;
 
@@ -105,6 +106,7 @@
             void invalidate();
 
     virtual sp<LayerBaseClient> getLayerBaseClient() const { return 0; }
+    virtual sp<Layer> getLayer() const { return 0; }
 
     virtual const char* getTypeId() const { return "LayerBase"; }