cc: Gather and lock/unlock SkDiscardablePixelRefs instead of skia::LazyPixelRefs.

skia/ext/pixel_ref_utils.h

+// Copyright 2013 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 SKIA_EXT_PIXEL_REF_UTILS_H_
+#define SKIA_EXT_PIXEL_REF_UTILS_H_
+
+#include <vector>
+
+#include "SkPicture.h"
+#include "SkRect.h"
+
+namespace skia {
+
+class SK_API PixelRefUtils {
+ public:
+
+  struct PositionPixelRef {
+    SkPixelRef* pixel_ref;
+    SkRect pixel_ref_rect;
+  };
+
+  static void GatherDiscardablePixelRefs(
+      SkPicture* picture,
+      std::vector<PositionPixelRef>* pixel_refs);
+};
+
+typedef std::vector<PixelRefUtils::PositionPixelRef> DiscardablePixelRefList;
+
+}  // namespace skia
+
+#endif