Make GrGLEffects use an interface to append their code.

include/core/SkString.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkString_DEFINED
@@ skipping 167 matching lines @@
     void prepend(const char text[]) { this->insert(0, text); }
     void prepend(const char text[], size_t len) { this->insert(0, text, len); }
     void prependUnichar(SkUnichar uni) { this->insertUnichar(0, uni); }
     void prependS32(int32_t value) { this->insertS32(0, value); }
     void prependS64(int32_t value, int minDigits = 0) { this->insertS64(0, value, minDigits); }
     void prependHex(uint32_t value, int minDigits = 0) { this->insertHex(0, value, minDigits); }
     void prependScalar(SkScalar value) { this->insertScalar((size_t)-1, value); }
 
     void printf(const char format[], ...) SK_PRINTF_LIKE(2, 3);
     void appendf(const char format[], ...) SK_PRINTF_LIKE(2, 3);
+    void appendf(const char format[], va_list);
     void prependf(const char format[], ...) SK_PRINTF_LIKE(2, 3);
 
     void remove(size_t offset, size_t length);
 
     SkString& operator+=(const SkString& s) { this->append(s); return *this; }
     SkString& operator+=(const char text[]) { this->append(text); return *this; }
     SkString& operator+=(const char c) { this->append(&c, 1); return *this; }
 
     /**
      *  Swap contents between this and other. This function is guaranteed
@@ skipping 46 matching lines @@
 /// Creates a new string and writes into it using a printf()-style format.
 SkString SkStringPrintf(const char* format, ...);
 
 // Specialized to take advantage of SkString's fast swap path. The unspecialized function is
 // declared in SkTypes.h and called by SkTSort.
 template <> inline void SkTSwap(SkString& a, SkString& b) {
     a.swap(b);
 }
 
 #endif