cc/paint: Remove PaintCanvas::peekPixels.

cc/paint/skia_paint_canvas.h

Index: cc/paint/skia_paint_canvas.h
diff --git a/cc/paint/skia_paint_canvas.h b/cc/paint/skia_paint_canvas.h
index 8dbcc83b5ad13bc269c1f46fca6a8ec3e4f3dd44..28c0e749b36c9bbf6bdd0d7d3f1448bb457dc9cc 100644
--- a/cc/paint/skia_paint_canvas.h
+++ b/cc/paint/skia_paint_canvas.h
@@ -28,15 +28,17 @@ class CC_PAINT_EXPORT SkiaPaintCanvas final : public PaintCanvas {
   explicit SkiaPaintCanvas(SkCanvas* canvas);
   explicit SkiaPaintCanvas(const SkBitmap& bitmap);
   explicit SkiaPaintCanvas(const SkBitmap& bitmap, const SkSurfaceProps& props);
+  explicit SkiaPaintCanvas(SkiaPaintCanvas&& other);
   ~SkiaPaintCanvas();
 
+  SkiaPaintCanvas& operator=(SkiaPaintCanvas&& other) = default;
+
   SkMetaData& getMetaData() override;
   SkImageInfo imageInfo() const override;
 
   void flush() override;
 
   SkISize getBaseLayerSize() const override;
-  bool peekPixels(SkPixmap* pixmap) override;
   bool readPixels(const SkImageInfo& dest_info,
                   void* dest_pixels,
                   size_t dest_row_bytes,
@@ -163,6 +165,8 @@ class CC_PAINT_EXPORT SkiaPaintCanvas final : public PaintCanvas {
  private:
   SkCanvas* canvas_;
   std::unique_ptr<SkCanvas> owned_;
+
+  DISALLOW_COPY_AND_ASSIGN(SkiaPaintCanvas);
 };
 
 }  // namespace cc