Cleanup: Removing unnecessary args/complexity in SkSurface_Base and friends

src/image/SkSurface.cpp

Index: src/image/SkSurface.cpp
===================================================================
--- src/image/SkSurface.cpp	(revision 8683)
+++ src/image/SkSurface.cpp	(working copy)
@@ -59,21 +59,21 @@
     return fCachedImage;
 }
 
-void SkSurface_Base::aboutToDraw(SkCanvas* canvas) {
+void SkSurface_Base::aboutToDraw() {
     this->dirtyGenerationID();
 
-    if (canvas) {
-        SkASSERT(canvas == fCachedCanvas);
-        SkASSERT(canvas->getSurfaceBase() == this);
-        canvas->setSurfaceBase(NULL);
+    if (NULL != fCachedCanvas) {
+        SkASSERT(fCachedCanvas->getSurfaceBase() == this || \
+                 NULL == fCachedCanvas->getSurfaceBase());
+        fCachedCanvas->setSurfaceBase(NULL);
     }
 
-    if (fCachedImage) {
+    if (NULL != 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->getRefCnt() > 1) {
-            this->onCopyOnWrite(fCachedImage, canvas);
+            this->onCopyOnWrite();
         }
 
         // regardless of copy-on-write, we must drop our cached image now, so
@@ -110,7 +110,7 @@
 }
 
 void SkSurface::notifyContentChanged() {
-    asSB(this)->aboutToDraw(NULL);
+    asSB(this)->aboutToDraw();
 }
 
 SkCanvas* SkSurface::getCanvas() {