android: Migrate old content readback to use async readback (and delegated renderer)

content/browser/android/transient_ui_resource.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 CONTENT_BROWSER_ANDROID_TRANSIENT_UI_RESOURCE_H_
+#define CONTENT_BROWSER_ANDROID_TRANSIENT_UI_RESOURCE_H_
+
+#include "base/memory/ref_counted.h"
+#include "cc/resources/ui_resource_client.h"
+#include "ui/gfx/size.h"
+
+namespace cc {
+
+class LayerTreeHost;
+class UIResourceBitmap;
+
+}
+
+namespace content {
+
+// This UIResourceClient immediately frees the pixels after it has been queried
+// once.  Subsequent GetBitmap() calls will return a small holder.
+class TransientUIResource : public cc::UIResourceClient {
+ public:
+  static scoped_ptr<TransientUIResource> Create(
+      cc::LayerTreeHost* host,
+      const cc::UIResourceBitmap& bitmap);
+  virtual ~TransientUIResource();
+
+  // UIResourceClient implementation.
+  virtual cc::UIResourceBitmap GetBitmap(cc::UIResourceId uid,
+                                         bool resource_lost) OVERRIDE;
+  cc::UIResourceId id() { return id_; }
+
+ protected:
+  TransientUIResource(cc::LayerTreeHost* host,
+                      const cc::UIResourceBitmap& bitmap);
+
+  scoped_ptr<cc::UIResourceBitmap> bitmap_;
+  cc::LayerTreeHost* host_;
+  cc::UIResourceId id_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TransientUIResource);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_TRANSIENT_UI_RESOURCE_H_