Revert of Move DstCopy on gpu into the GrXferProcessor.

src/gpu/GrXferProcessor.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 "GrXferProcessor.h"
-#include "gl/GrGLCaps.h"
-
-GrXferProcessor::GrXferProcessor() : fWillReadDstColor(false), fDstCopyTextureOffset() {
-}
-
-GrXferProcessor::GrXferProcessor(const GrDeviceCoordTexture* dstCopy, bool willReadDstColor)
-    : fWillReadDstColor(willReadDstColor)
-    , fDstCopyTextureOffset() {
-    if (dstCopy && dstCopy->texture()) {
-        fDstCopy.reset(dstCopy->texture());
-        fDstCopyTextureOffset = dstCopy->offset();
-        SkASSERT(kTopLeft_GrSurfaceOrigin == fDstCopy.getTexture()->origin());
-        this->addTextureAccess(&fDstCopy);
-    }
-}
-
-void GrXferProcessor::getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const {
-    uint32_t key = this->willReadDstColor() ? 0x1 : 0x0;
-    b->add32(key);
-    this->onGetGLProcessorKey(caps, b);
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
-GrXferProcessor* GrXPFactory::createXferProcessor(const GrProcOptInfo& colorPOI,
-                                                  const GrProcOptInfo& coveragePOI,
-                                                  const GrDeviceCoordTexture* dstCopy,
-                                                  const GrDrawTargetCaps& caps) const {
-#ifdef SK_DEBUG
-    if (this->willReadDstColor()) {
-        if (!caps.dstReadInShaderSupport()) {
-            SkASSERT(dstCopy && dstCopy->texture());
-        } else {
-            SkASSERT(!dstCopy || !dstCopy->texture()); 
-        }
-    } else {
-        SkASSERT(!dstCopy || !dstCopy->texture()); 
-
-    }
-#endif
-    return this->onCreateXferProcessor(colorPOI, coveragePOI, dstCopy);
-}
-
-bool GrXPFactory::willNeedDstCopy(const GrDrawTargetCaps& caps) const {
-    return (this->willReadDstColor() && !caps.dstReadInShaderSupport());
-}
-