cc/paint: Remove PaintCanvas::peekPixels.

ui/gfx/canvas.h

Index: ui/gfx/canvas.h
diff --git a/ui/gfx/canvas.h b/ui/gfx/canvas.h
index 4fcb4bcfbdfe563610198d12239de0f6e12ec6e4..29120504e441c45d142b7378521bab37bcbfccbc 100644
--- a/ui/gfx/canvas.h
+++ b/ui/gfx/canvas.h
@@ -11,10 +11,11 @@
 #include <vector>
 
 #include "base/macros.h"
+#include "base/optional.h"
 #include "base/strings/string16.h"
 #include "cc/paint/paint_canvas.h"
 #include "cc/paint/paint_flags.h"
-#include "cc/paint/paint_surface.h"
+#include "cc/paint/skia_paint_canvas.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/text_constants.h"
@@ -475,6 +476,10 @@ class GFX_EXPORT Canvas {
 
   // TODO(enne): rename sk_canvas members and interface.
   cc::PaintCanvas* sk_canvas() { return canvas_; }
+  SkBitmap& get_bitmap() {

[enne (OOO), 2017/03/21 00:46:38]

Maybe ToBitmap() should return bitmap_ if it exists? and then you can just use
ToBitmap instead of get_bitmap?

[vmpstr, 2017/03/21 17:47:12]

Oh, I completely missed that there is ToBitmap here. It seems that it's only
used in unittests. I've updated it to just return the bitmap instead of doing a
readback and now am using it in canvas_paint_mac.mm. 

I could also change it to do a readback if the bitmap doesn't exist, but I don't
think there are usecases right now that do this. WDYT?

[enne (OOO), 2017/03/21 17:51:02]

Oh, even better! If that's always the case, then let's do that!

+    DCHECK(bitmap_);
+    return bitmap_.value();
+  }
   float image_scale() const { return image_scale_; }
 
  private:
@@ -496,6 +501,7 @@ class GFX_EXPORT Canvas {
                           bool filter,
                           const cc::PaintFlags& flags,
                           bool remove_image_scale);
+  cc::PaintCanvas* CreateOwnedCanvas(const Size& size, bool is_opaque);
 
   // The device scale factor at which drawing on this canvas occurs.
   // An additional scale can be applied via Canvas::Scale(). However,
@@ -503,10 +509,11 @@ class GFX_EXPORT Canvas {
   float image_scale_;
 
   // canvas_ is our active canvas object. Sometimes we are also the owner,
-  // in which case surface_ will be set. Other times we are just
-  // borrowing someone else's canvas, in which case canvas_ will point there
-  // but surface_ will be null.
-  sk_sp<cc::PaintSurface> surface_;
+  // in which case bitmap_ and owned_canvas_ will be set. Other times we are
+  // just borrowing someone else's canvas, in which case canvas_ will point
+  // there but bitmap_ and owned_canvas_ will not exist.
+  base::Optional<SkBitmap> bitmap_;
+  base::Optional<cc::SkiaPaintCanvas> owned_canvas_;
   cc::PaintCanvas* canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(Canvas);