Move canvas->surface association to the device subclasses

src/image/SkSurface.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"
@@ skipping 51 matching lines @@
 }
 
 SkSurface_Base::SkSurface_Base(const SkImageInfo& info, const SkSurfaceProps* props)
     : INHERITED(info, props)
 {
     fCachedCanvas = NULL;
     fCachedImage = NULL;
 }
 
 SkSurface_Base::~SkSurface_Base() {
-    // in case the canvas outsurvives us, we null the callback
-    if (fCachedCanvas) {
-        fCachedCanvas->setSurfaceBase(NULL);
-    }
-
     SkSafeUnref(fCachedImage);
     SkSafeUnref(fCachedCanvas);
 }
 
 void SkSurface_Base::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y, const SkPaint* paint) {
     SkImage* image = this->newImageSnapshot(kYes_Budgeted);
     if (image) {
         canvas->drawImage(image, x, y, paint);
         image->unref();
     }
 }
 
 void SkSurface_Base::aboutToDraw(ContentChangeMode mode) {
     this->dirtyGenerationID();
 
-    SkASSERT(!fCachedCanvas || fCachedCanvas->getSurfaceBase() == this);
-
     if (fCachedImage) {
         // the surface may need to fork its backend, if its sharing it with
         // the cached image. Note: we only call if there is an outstanding owner
         // on the image (besides us).
         if (!fCachedImage->unique()) {
             this->onCopyOnWrite(mode);
         }
 
         // regardless of copy-on-write, we must drop our cached image now, so
         // that the next request will get our new contents.
         fCachedImage->unref();
         fCachedImage = NULL;
     } else if (kDiscard_ContentChangeMode == mode) {
         this->onDiscard();
     }
 }
 
 uint32_t SkSurface_Base::newGenerationID() {
-    SkASSERT(!fCachedCanvas || fCachedCanvas->getSurfaceBase() == this);
     static int32_t gID;
     return sk_atomic_inc(&gID) + 1;
 }
 
 static SkSurface_Base* asSB(SkSurface* surface) {
     return static_cast<SkSurface_Base*>(surface);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
@@ skipping 60 matching lines @@
     return NULL;
 }
 
 SkSurface* SkSurface::NewRenderTarget(GrContext*, Budgeted, const SkImageInfo&, int,
                                       const SkSurfaceProps*) {
     return NULL;
 }
 
 
 #endif