Integrating SkSurface with SkDeferredCanvas

src/image/SkSurface.cpp

Index: src/image/SkSurface.cpp
===================================================================
--- src/image/SkSurface.cpp	(revision 8402)
+++ src/image/SkSurface.cpp	(working copy)
@@ -59,21 +59,19 @@
     return fCachedImage;
 }
 
-void SkSurface_Base::aboutToDraw(SkCanvas* canvas) {
+void SkSurface_Base::aboutToDraw(SkCanvas* canvas, bool overwrite) {
     this->dirtyGenerationID();
 
-    if (canvas) {
-        SkASSERT(canvas == fCachedCanvas);
-        SkASSERT(canvas->getSurfaceBase() == this);
-        canvas->setSurfaceBase(NULL);
-    }
+    SkASSERT(canvas == fCachedCanvas);
+    SkASSERT(canvas->getSurfaceBase() == this || NULL == fCachedImage);
+    canvas->setSurfaceBase(NULL);
 
     if (fCachedImage) {
-        // the surface may need to fork its backend, if its sharing it with
+        // the surface may need to fork its backend, if it's sharing it with
         // the cached image. Note: we only call if there is an outstanding owner
         // on the image (besides us).
         if (fCachedImage->getRefCnt() > 1) {
-            this->onCopyOnWrite(fCachedImage, canvas);
+            this->onCopyOnWrite(fCachedImage, canvas, overwrite);
         }
 
         // regardless of copy-on-write, we must drop our cached image now, so
@@ -109,8 +107,8 @@
     return fGenerationID;
 }
 
-void SkSurface::notifyContentChanged() {
-    asSB(this)->aboutToDraw(NULL);
+void SkSurface::notifyContentChanged(bool overwrite) {
+    asSB(this)->aboutToDraw(this->getCanvas(), overwrite);
 }
 
 SkCanvas* SkSurface::getCanvas() {