allow SkUserConfig.h to control NOGPU

src/image/SkSurface_Gpu.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkSurface_Base.h"
 #include "SkImagePriv.h"
 #include "SkCanvas.h"
 #include "SkGpuDevice.h"
 
+#if SK_SUPPORT_GPU
+
 class SkSurface_Gpu : public SkSurface_Base {
 public:
     SK_DECLARE_INST_COUNT(SkSurface_Gpu)
 
     SkSurface_Gpu(GrRenderTarget*, const SkSurfaceProps*, bool doClear);
     virtual ~SkSurface_Gpu();
 
     virtual SkCanvas* onNewCanvas() SK_OVERRIDE;
     virtual SkSurface* onNewSurface(const SkImageInfo&) SK_OVERRIDE;
     virtual SkImage* onNewImageSnapshot() SK_OVERRIDE;
@@ skipping 124 matching lines @@
     desc.fSampleCnt = sampleCount;
 
     SkAutoTUnref<GrTexture> tex(ctx->refScratchTexture(desc, GrContext::kExact_ScratchTexMatch));
 
     if (NULL == tex) {
         return NULL;
     }
 
     return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget(), props, true));
 }
+
+#endif