Fix rendering artifacts in pull-saveLayers-forward mode

src/gpu/GrPictureUtils.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrPictureUtils.h"
 #include "SkDevice.h"
 #include "SkDraw.h"
@@ skipping 119 matching lines @@
 
         if (device->fAlreadyDrawn) {
             return;
         }
 
         device->fInfo.fRestoreOpID = fPicture->EXPERIMENTAL_curOpID();
         device->fInfo.fCTM = *draw.fMatrix;
         device->fInfo.fCTM.postTranslate(SkIntToScalar(-device->getOrigin().fX),
                                          SkIntToScalar(-device->getOrigin().fY));
 
-        // We need the x & y values that will yield 'getOrigin' when transformed
-        // by 'draw.fMatrix'.
-        device->fInfo.fOffset.iset(device->getOrigin());
-
-        SkMatrix invMatrix;
-        if (draw.fMatrix->invert(&invMatrix)) {
-            invMatrix.mapPoints(&device->fInfo.fOffset, 1);
-        } else {
-            device->fInfo.fValid = false;
-        }
+        device->fInfo.fOffset = device->getOrigin();
 
         if (NeedsDeepCopy(paint)) {
             // This NULL acts as a signal that the paint was uncopyable (for now)
             device->fInfo.fPaint = NULL;
             device->fInfo.fValid = false;
         } else {
             device->fInfo.fPaint = SkNEW_ARGS(SkPaint, (paint));
         }
 
         fAccelData->addSaveLayerInfo(device->fInfo);
@@ skipping 127 matching lines @@
 void GatherGPUInfo(SkPicture* pict, GPUAccelData* accelData) {
     if (0 == pict->width() || 0 == pict->height()) {
         return ;
     }
 
     GrGatherDevice device(pict->width(), pict->height(), pict, accelData, 0);
     GrGatherCanvas canvas(&device, pict);
 
     canvas.gather();
 }