Revert "Change SkCanvas to *not* inherit from SkRefCnt"

This reverts commit 824075071885b6b741c141cbe2134d8345d34589.

Reason for revert: Breaking WebView (chromium:663959)

Original change's description:
> Change SkCanvas to *not* inherit from SkRefCnt
> 
> Definitely tricky for classes like SkNWayCanvas, where the caller (today)
> need not pay attention to ownership of the canvases it gave the NWay
> (after this CL, the caller *must* managed ownership)
> 
> BUG=skia:
> 
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4441
> 
> DOCS_PREVIEW= https://skia.org/?cl=4441
> 
> Change-Id: Ib1ac07a3cdf0686d78e7aaa4735d45cc90bea081
> Reviewed-on: https://skia-review.googlesource.com/4441
> Commit-Queue: Mike Reed <reed@google.com>
> Reviewed-by: Florin Malita <fmalita@chromium.org>
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> 

TBR=djsollen@google.com,mtklein@google.com,halcanary@google.com,robertphillips@google.com,fmalita@chromium.org,fmalita@google.com,reed@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I5e3b3e876b7d2c09833cf841801321033b6b968b
Reviewed-on: https://skia-review.googlesource.com/4687
Commit-Queue: Heather Miller <hcm@google.com>
Reviewed-by: Heather Miller <hcm@google.com>

3 files changed, 3 insertions, 3 deletions

diff --git a/tools/lua/lua_pictures.cpp b/tools/lua/lua_pictures.cpp
index 639a5227ee..bd8fda1569 100644
--- a/tools/lua/lua_pictures.cpp
+++ b/tools/lua/lua_pictures.cpp
@@ -145,7 +145,7 @@ int tool_main(int argc, char** argv) {
 
             auto pic(load_picture(path));
             if (pic.get()) {
-                std::unique_ptr<SkLuaCanvas> canvas(
+                sk_sp<SkLuaCanvas> canvas(
                                     new SkLuaCanvas(SkScalarCeilToInt(pic->cullRect().width()),
                                                     SkScalarCeilToInt(pic->cullRect().height()),
                                                     L.get(), gAccumulateFunc));
diff --git a/tools/skiaserve/Request.h b/tools/skiaserve/Request.h
index 4058d7ce7e..6b065a2bf8 100644
--- a/tools/skiaserve/Request.h
+++ b/tools/skiaserve/Request.h
@@ -63,7 +63,7 @@ struct Request {
     SkColor getPixel(int x, int y);
 
     UploadContext* fUploadContext;
-    std::unique_ptr<SkDebugCanvas> fDebugCanvas;
+    sk_sp<SkDebugCanvas> fDebugCanvas;
     UrlDataManager fUrlDataManager;
 
 private:
diff --git a/tools/skp_parser.cpp b/tools/skp_parser.cpp
index 887c50d182..d242524566 100644
--- a/tools/skp_parser.cpp
+++ b/tools/skp_parser.cpp
@@ -34,7 +34,7 @@ int main(int argc, char** argv) {
     SkISize size = pic->cullRect().roundOut().size();
     SkDebugCanvas debugCanvas(size.width(), size.height());
     pic->playback(&debugCanvas);
-    std::unique_ptr<SkCanvas> nullCanvas = SkMakeNullCanvas();
+    sk_sp<SkCanvas> nullCanvas(SkCreateNullCanvas());
     UrlDataManager dataManager(SkString("data"));
     Json::Value json = debugCanvas.toJSON(
             dataManager, debugCanvas.getSize(), nullCanvas.get());