Modernize and trim down SkOnce.

src/effects/gradients/SkGradientShaderPriv.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGradientShaderPriv_DEFINED
 #define SkGradientShaderPriv_DEFINED
 
@@ skipping 124 matching lines @@
         uint16_t*         fCache16Storage;    // Storage for fCache16, allocated on demand.
         SkMallocPixelRef* fCache32PixelRef;
         const unsigned    fCacheAlpha;        // The alpha value we used when we computed the cache.
                                               // Larger than 8bits so we can store uninitialized
                                               // value.
         const bool        fCacheDither;       // The dither flag used when we computed the cache.
 
         const SkGradientShaderBase& fShader;
 
         // Make sure we only initialize the caches once.
-        bool    fCache16Inited, fCache32Inited;
-        SkMutex fCache16Mutex, fCache32Mutex;
+        SkOnce fCache16InitOnce,
+               fCache32InitOnce;
 
         static void initCache16(GradientShaderCache* cache);
         static void initCache32(GradientShaderCache* cache);
 
         static void Build16bitCache(uint16_t[], SkColor c0, SkColor c1, int count, bool dither);
         static void Build32bitCache(SkPMColor[], SkColor c0, SkColor c1, int count,
                                     U8CPU alpha, uint32_t gradFlags, bool dither);
     };
 
     class GradientShaderBaseContext : public SkShader::Context {
@@ skipping 290 matching lines @@
     GrGLSLProgramDataManager::UniformHandle fColorStartUni;
     GrGLSLProgramDataManager::UniformHandle fColorMidUni;
     GrGLSLProgramDataManager::UniformHandle fColorEndUni;
 
     typedef GrGLSLFragmentProcessor INHERITED;
 };
 
 #endif
 
 #endif