Revert[2] "Change SkCanvas to *not* inherit from SkRefCnt"

Changes over original:
- conditionalize ownership in SkPictureRecorder
- conditionalize ownership in SkCanvasStateUtils

This reverts commit b613c266df48cf45296ecc23d1bd7098c84bb7ba.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4742

Change-Id: Ib25514d6f546c69b6650b5c957403b04f7380dc2
Reviewed-on: https://skia-review.googlesource.com/4742
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>

2 files changed, 4 insertions, 7 deletions

diff --git a/src/image/SkSurface.cpp b/src/image/SkSurface.cpp
index 38bab9e32f..3d6670f169 100644
--- a/src/image/SkSurface.cpp
+++ b/src/image/SkSurface.cpp
@@ -58,14 +58,12 @@ SkSurfaceProps::SkSurfaceProps(const SkSurfaceProps& other)
 SkSurface_Base::SkSurface_Base(int width, int height, const SkSurfaceProps* props)
     : INHERITED(width, height, props)
 {
-    fCachedCanvas = nullptr;
     fCachedImage = nullptr;
 }
 
 SkSurface_Base::SkSurface_Base(const SkImageInfo& info, const SkSurfaceProps* props)
     : INHERITED(info, props)
 {
-    fCachedCanvas = nullptr;
     fCachedImage = nullptr;
 }
 
@@ -76,7 +74,6 @@ SkSurface_Base::~SkSurface_Base() {
     }
 
     SkSafeUnref(fCachedImage);
-    SkSafeUnref(fCachedCanvas);
 }
 
 void SkSurface_Base::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y, const SkPaint* paint) {
diff --git a/src/image/SkSurface_Base.h b/src/image/SkSurface_Base.h
index 8351bb87e6..a8c1d8f0a4 100644
--- a/src/image/SkSurface_Base.h
+++ b/src/image/SkSurface_Base.h
@@ -89,8 +89,8 @@ public:
     uint32_t newGenerationID();
 
 private:
-    SkCanvas*   fCachedCanvas;
-    SkImage*    fCachedImage;
+    std::unique_ptr<SkCanvas>   fCachedCanvas;
+    SkImage*                    fCachedImage;
 
     void aboutToDraw(ContentChangeMode mode);
 
@@ -106,12 +106,12 @@ private:
 
 SkCanvas* SkSurface_Base::getCachedCanvas() {
     if (nullptr == fCachedCanvas) {
-        fCachedCanvas = this->onNewCanvas();
+        fCachedCanvas = std::unique_ptr<SkCanvas>(this->onNewCanvas());
         if (fCachedCanvas) {
             fCachedCanvas->setSurfaceBase(this);
         }
     }
-    return fCachedCanvas;
+    return fCachedCanvas.get();
 }
 
 sk_sp<SkImage> SkSurface_Base::refCachedImage(SkBudgeted budgeted, ForceUnique unique) {