Implement SkBaseDevice snapshot support

src/image/SkSurface.cpp

Index: src/image/SkSurface.cpp
diff --git a/src/image/SkSurface.cpp b/src/image/SkSurface.cpp
index 2d3fa2bf7a4eeee1e0d46943c40d45e8d73ee2b7..5208fdc3342b98ffdfdbd10a443598d7d21aed42 100644
--- a/src/image/SkSurface.cpp
+++ b/src/image/SkSurface.cpp
@@ -58,23 +58,15 @@ SkSurface_Base::SkSurface_Base(int width, int height, const SkSurfaceProps* prop
     : INHERITED(width, height, props)
 {
     fCachedCanvas = NULL;
-    fCachedImage = NULL;
 }
 
 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);
 }
 
@@ -86,30 +78,7 @@ void SkSurface_Base::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y, const SkPa
     }
 }
 
-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;
 }
@@ -125,7 +94,6 @@ SkSurface::SkSurface(int width, int height, const SkSurfaceProps* props)
 {
     SkASSERT(fWidth > 0);
     SkASSERT(fHeight > 0);
-    fGenerationID = 0;
 }
 
 SkSurface::SkSurface(const SkImageInfo& info, const SkSurfaceProps* props)
@@ -133,18 +101,6 @@ SkSurface::SkSurface(const SkImageInfo& info, const SkSurfaceProps* props)
 {
     SkASSERT(fWidth > 0);
     SkASSERT(fHeight > 0);
-    fGenerationID = 0;
-}
-
-uint32_t SkSurface::generationID() {
-    if (0 == fGenerationID) {
-        fGenerationID = asSB(this)->newGenerationID();
-    }
-    return fGenerationID;
-}
-
-void SkSurface::notifyContentWillChange(ContentChangeMode mode) {
-    asSB(this)->aboutToDraw(mode);
 }
 
 SkCanvas* SkSurface::getCanvas() {
@@ -152,9 +108,7 @@ SkCanvas* SkSurface::getCanvas() {
 }
 
 SkImage* SkSurface::newImageSnapshot(Budgeted budgeted) {
-    SkImage* image = asSB(this)->getCachedImage(budgeted);
-    SkSafeRef(image);   // the caller will call unref() to balance this
-    return image;
+    return asSB(this)->onNewImageSnapshot(budgeted);
 }
 
 SkSurface* SkSurface::newSurface(const SkImageInfo& info) {