clean-up/simplify all dump() APIs

remove the scratch buffer parameter and use
String8::appendFormat() instead.

Change-Id: Ib96c91617c8e7292de87433d15cf6232b7d591b0
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 2765db1..2c06f1a 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -304,9 +304,9 @@
 
 
     /* always call base class first */
-    virtual void dump(String8& result, char* scratch, size_t size) const;
-    virtual void shortDump(String8& result, char* scratch, size_t size) const;
-    virtual void dumpStats(String8& result, char* buffer, size_t SIZE) const;
+    virtual void dump(String8& result) const;
+    virtual void shortDump(String8& result) const;
+    virtual void dumpStats(String8& result) const;
     virtual void clearStats();
 
 protected: