cc: Add some impl-side painting stub classes and APIs

cc/picture_pile.h

+// Copyright 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_PICTURE_PILE_H_
+#define CC_PICTURE_PILE_H_
+
+#include "base/basictypes.h"
+#include "cc/cc_export.h"
+#include "cc/picture.h"
+#include "cc/scoped_ptr_vector.h"
+#include "ui/gfx/rect.h"
+#include "ui/gfx/size.h"
+
+namespace cc {
+
+class CC_EXPORT PicturePile {
+public:
+  PicturePile();
+  ~PicturePile();
+
+  // Mark a portion of the PicturePile as invalid and needing to be re-recorded
+  // the next time update is called.
+  void invalidate(gfx::Rect);
+
+  // Resize the PicturePile, invalidating / dropping recorded pictures as necessary.
+  void resize(gfx::Size);
+
+  // Rerecord parts of the picture that are invalid.
+  void update(ContentLayerClient* painter);
+
+  // Update other with a shallow copy of this (main => compositor thread commit)
+  void pushPropertiesTo(PicturePile& other);
+
+  // Clone a paint-safe version of this picture (with cloned PicturePileRecords)
+  scoped_ptr<PicturePile> cloneForDrawing(gfx::Rect rect);
+
+  // Raster a subrect of this PicturePile into the given canvas.
+  // It's only safe to call paint on a cloned version.
+  void paint(SkCanvas* canvas, gfx::Rect rect);
+
+protected:
+  std::vector<scoped_refptr<Picture> > pile_;
+  gfx::Size size_;
+
+  DISALLOW_COPY_AND_ASSIGN(PicturePile);
+};
+
+}  // namespace cc
+
+#endif  // CC_PICTURE_PILE_H_