WIP RasterCanvasLayerAllocator experiment 2

src/core/SkManagedBitmapDevice.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkManagedBitmapDevice_DEFINED
+#define SkManagedBitmapDevice_DEFINED
+
+#include "SkBitmapDevice.h"
+
+class SkBitmap;
+class SkSurfaceProps;
+
+/**
+ * A BitmapDevice whose raster backing is managed by the OS or some external
+ * library.
+ */
+
+class SkManagedBitmapDevice : public SkBitmapDevice {
+public:
+    SkManagedBitmapDevice(const SkBitmap& bitmap,
+                          const SkSurfaceProps& surfaceProps,
+                          void (*deallocator) (void*),
+                          void* deallocatorPayload);
+
+    ~SkManagedBitmapDevice() override;
+private:
+
+    /// An implementation-dependent function to call when releasing
+    /// the raster backing.
+    void (*fDeallocator)(void* payload);
+
+    void* fDeallocatorPayload;
+
+    typedef SkBitmapDevice INHERITED;
+};
+
+#endif // SkManagedBitmapDevice_DEFINED
+