remove fClipStack and attach/deattach-from-canvas

src/pdf/SkPDFDevice.cpp

Index: src/pdf/SkPDFDevice.cpp
diff --git a/src/pdf/SkPDFDevice.cpp b/src/pdf/SkPDFDevice.cpp
index 8370eabd6aa587d61706262e172ff73eff35b2da..4181defc5ddc62a47542ba5ab9ca88490a5644f2 100644
--- a/src/pdf/SkPDFDevice.cpp
+++ b/src/pdf/SkPDFDevice.cpp
@@ -653,7 +653,6 @@ SkPDFDevice::SkPDFDevice(SkISize pageSize, SkScalar rasterDpi, SkPDFDocument* do
     , fPageSize(pageSize)
     , fContentSize(pageSize)
     , fExistingClipRegion(SkIRect::MakeSize(pageSize))
-    , fClipStack(nullptr)
     , fRasterDpi(rasterDpi)
     , fDocument(doc) {
     SkASSERT(pageSize.width() > 0);
@@ -1405,19 +1404,6 @@ SkImageInfo SkPDFDevice::imageInfo() const {
     return info;
 }
 
-void SkPDFDevice::onAttachToCanvas(SkCanvas* canvas) {
-    INHERITED::onAttachToCanvas(canvas);
-
-    // Canvas promises that this ptr is valid until onDetachFromCanvas is called
-    fClipStack = canvas->getClipStack();
-}
-
-void SkPDFDevice::onDetachFromCanvas() {
-    INHERITED::onDetachFromCanvas();
-
-    fClipStack = nullptr;
-}
-
 sk_sp<SkSurface> SkPDFDevice::makeSurface(const SkImageInfo& info, const SkSurfaceProps& props) {
     return SkSurface::MakeRaster(info, &props);
 }