Move prepareForExternalIO implementation from GrContext to GrDrawingManager

src/gpu/GrDrawContext.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 "GrBatchTest.h"
 #include "GrColor.h"
 #include "GrDrawContext.h"
@@ skipping 1097 matching lines @@
 }
 
 void GrDrawContext::prepareForExternalIO() {
     ASSERT_SINGLE_OWNER
     RETURN_IF_ABANDONED
     SkDEBUGCODE(this->validate();)
     GR_AUDIT_TRAIL_AUTO_FRAME(fAuditTrail, "GrDrawContext::prepareForExternalIO");
 
     ASSERT_OWNED_RESOURCE(fRenderTarget);
 
-    fDrawingManager->getContext()->prepareSurfaceForExternalIO(fRenderTarget.get());
+    fDrawingManager->prepareSurfaceForExternalIO(fRenderTarget.get());
 }
 
 void GrDrawContext::drawNonAAFilledRect(const GrClip& clip,
                                         const GrPaint& paint,
                                         const SkMatrix& viewMatrix,
                                         const SkRect& rect,
                                         const SkRect* localRect,
                                         const SkMatrix* localMatrix,
                                         const GrUserStencilSettings* ss,
                                         bool useHWAA) {
@@ skipping 299 matching lines @@
 
 void GrDrawContext::drawBatch(const GrPipelineBuilder& pipelineBuilder, const GrClip& clip,
                               GrDrawBatch* batch) {
     ASSERT_SINGLE_OWNER
     RETURN_IF_ABANDONED
     SkDEBUGCODE(this->validate();)
     GR_AUDIT_TRAIL_AUTO_FRAME(fAuditTrail, "GrDrawContext::drawBatch");
 
     this->getDrawTarget()->drawBatch(pipelineBuilder, this, clip, batch);
 }