Make GrGLEffects use an interface to append their code.

src/ports/SkDebug_stdio.cpp

Index: src/ports/SkDebug_stdio.cpp
===================================================================
--- src/ports/SkDebug_stdio.cpp	(revision 8005)
+++ src/ports/SkDebug_stdio.cpp	(working copy)
@@ -9,16 +9,12 @@
 
 #include "SkTypes.h"
 
-static const size_t kBufferSize = 2048;
-
 #include <stdarg.h>
 #include <stdio.h>
 
 void SkDebugf(const char format[], ...) {
-    char    buffer[kBufferSize + 1];
     va_list args;
     va_start(args, format);
-    vsnprintf(buffer, kBufferSize, format, args);
+    vfprintf(stderr, format, args);
     va_end(args);
-    fprintf(stderr, "%s", buffer);
 }