diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/lazy/SkDiscardablePixelRef.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/skia/trunk/src/lazy/SkDiscardablePixelRef.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDiscardablePixelRef_DEFINED
+#define SkDiscardablePixelRef_DEFINED
+
+#include "SkDiscardableMemory.h"
+#include "SkImageGenerator.h"
+#include "SkImageInfo.h"
+#include "SkPixelRef.h"
+
+/**
+ *  A PixelRef backed by SkDiscardableMemory, with the ability to
+ *  re-generate the pixels (via a SkImageGenerator) if the DM is
+ *  purged.
+ *
+ *  Since SkColorTable is reference-counted, we do not support indexed
+ *  color with this class; there would be no way for the discardable
+ *  memory system to unref the color table.
+ */
+class SkDiscardablePixelRef : public SkPixelRef {
+public:
+    SK_DECLARE_INST_COUNT(SkDiscardablePixelRef)
+    SK_DECLARE_UNFLATTENABLE_OBJECT()
+
+protected:
+    ~SkDiscardablePixelRef();
+
+    virtual bool onNewLockPixels(LockRec*) SK_OVERRIDE;
+    virtual void onUnlockPixels() SK_OVERRIDE;
+    virtual bool onLockPixelsAreWritable() const SK_OVERRIDE { return false; }
+
+    virtual SkData* onRefEncodedData() SK_OVERRIDE {
+        return fGenerator->refEncodedData();
+    }
+
+private:
+    SkImageGenerator* const fGenerator;
+    SkDiscardableMemory::Factory* const fDMFactory;
+    const size_t fRowBytes;
+    // These const members should not change over the life of the
+    // PixelRef, since the SkBitmap doesn't expect them to change.
+
+    SkDiscardableMemory* fDiscardableMemory;
+
+    /* Takes ownership of SkImageGenerator. */
+    SkDiscardablePixelRef(const SkImageInfo&, SkImageGenerator*,
+                          size_t rowBytes,
+                          SkDiscardableMemory::Factory* factory);
+
+    friend bool SkInstallDiscardablePixelRef(SkImageGenerator*,
+                                             SkBitmap*,
+                                             SkDiscardableMemory::Factory*);
+
+    typedef SkPixelRef INHERITED;
+};
+
+#endif  // SkDiscardablePixelRef_DEFINED