Move canvas->surface association to the device subclasses

src/image/SkSurface_Gpu.cpp

Index: src/image/SkSurface_Gpu.cpp
diff --git a/src/image/SkSurface_Gpu.cpp b/src/image/SkSurface_Gpu.cpp
index 5fb4b718a27b3a664a00cf1d055166ddf4dd70c2..49a668ec3ffaa81a1f6537eb65318baa5817e03d 100644
--- a/src/image/SkSurface_Gpu.cpp
+++ b/src/image/SkSurface_Gpu.cpp
@@ -7,7 +7,6 @@
 
 #include "SkSurface_Gpu.h"
 
-#include "GrGpuResourcePriv.h"
 #include "SkCanvas.h"
 #include "SkGpuDevice.h"
 #include "SkImage_Base.h"
@@ -21,9 +20,12 @@
 SkSurface_Gpu::SkSurface_Gpu(SkGpuDevice* device)
     : INHERITED(device->width(), device->height(), &device->surfaceProps())
     , fDevice(SkRef(device)) {
+    fDevice->setSurface(this);
 }
 
 SkSurface_Gpu::~SkSurface_Gpu() {
+    // In case the device outlives this instance, make sure device does not try to access this.
+    fDevice->setSurface(NULL);
     fDevice->unref();
 }
 
@@ -69,22 +71,7 @@ void SkSurface_Gpu::onCopyOnWrite(ContentChangeMode mode) {
     SkImage* image = this->getCachedImage(kNo_Budgeted);
     SkASSERT(image);
     if (rt->asTexture() == SkTextureImageGetTexture(image)) {
-        GrRenderTarget* oldRT = this->fDevice->accessRenderTarget();
-        SkSurface::Budgeted budgeted = oldRT->resourcePriv().isBudgeted() ? kYes_Budgeted :
-                kNo_Budgeted;
-        SkAutoTUnref<GrRenderTarget> newRT(
-            SkGpuDevice::CreateRenderTarget(oldRT->getContext(), budgeted, fDevice->imageInfo(),
-                                            oldRT->numSamples()));
-
-        if (kRetain_ContentChangeMode == mode && !oldRT->wasDestroyed() && newRT) {
-            oldRT->getContext()->copySurface(newRT, oldRT);
-        }
-
-        SkASSERT(this->getCachedCanvas());
-        SkASSERT(this->getCachedCanvas()->getDevice() == fDevice);
-
-        this->fDevice->swapRenderTarget(newRT);
-
+        fDevice->detachBackendRenderTarget(kRetain_ContentChangeMode == mode);
         SkTextureImageApplyBudgetedDecision(image);
     } else if (kDiscard_ContentChangeMode == mode) {
         this->SkSurface_Gpu::onDiscard();