Modernize and trim down SkOnce.

tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp

 
 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMutex.h"
 #include "SkOnce.h"
@@ skipping 109 matching lines @@
     }
 }
 
 static GrGLFuncPtr command_buffer_get_gl_proc(void* ctx, const char name[]) {
     if (!gfFunctionsLoadedSuccessfully) {
         return nullptr;
     }
     return gfGetProcAddress(name);
 }
 
-SK_DECLARE_STATIC_ONCE(loadCommandBufferOnce);
 static void load_command_buffer_once() {
-    SkOnce(&loadCommandBufferOnce, load_command_buffer_functions);
+    static SkOnce once;
+    once(load_command_buffer_functions);
 }
 
 static const GrGLInterface* create_command_buffer_interface() {
     load_command_buffer_once();
     if (!gfFunctionsLoadedSuccessfully) {
         return nullptr;
     }
     return GrGLAssembleGLESInterface(gLibrary, command_buffer_get_gl_proc);
 }
 
@@ skipping 221 matching lines @@
     return result;
 }
 
 int CommandBufferGLTestContext::getSampleCount() {
     EGLint result = 0;
     gfGetConfigAttrib(fDisplay, static_cast<EGLConfig>(fConfig), EGL_SAMPLES, &result);
     return result;
 }
 
 }  // namespace sk_gpu_test