Make readpixels work on GrTextures

src/image/SkImage_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 "SkImage_Gpu.h"
 #include "GrContext.h"
 #include "GrDrawContext.h"
@@ skipping 230 matching lines @@
     return SkNEW_ARGS(SkImage_Gpu, (dstDesc.fWidth, dstDesc.fHeight, kOpaque_SkAlphaType, dst, 0,
                                     budgeted));
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 GrTexture* GrDeepCopyTexture(GrTexture* src, bool budgeted) {
     GrContext* ctx = src->getContext();
 
     GrSurfaceDesc desc = src->desc();
-    // need to be a rendertarget for readpixels to work, instead of kNone_GrSurfaceFlags
-    desc.fFlags = kRenderTarget_GrSurfaceFlag;
     GrTexture* dst = ctx->textureProvider()->createTexture(desc, budgeted, NULL, 0);
     if (!dst) {
         return NULL;
     }
     
     const SkIRect srcR = SkIRect::MakeWH(desc.fWidth, desc.fHeight);
     const SkIPoint dstP = SkIPoint::Make(0, 0);
     ctx->copySurface(dst, src, srcR, dstP, GrContext::kFlushWrites_PixelOp);
     return dst;
 }