aura: Allow delegated frames to be used by more than one impl layer.

cc/layers/delegated_frame_provider.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 CC_LAYERS_DELEGATED_FRAME_PROVIDER_H_
+#define CC_LAYERS_DELEGATED_FRAME_PROVIDER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "cc/base/cc_export.h"
+#include "cc/resources/return_callback.h"
+#include "cc/resources/returned_resource.h"
+#include "ui/gfx/rect_f.h"
+#include "ui/gfx/size.h"
+
+namespace cc {
+class DelegatedFrameData;
+class DelegatedFrameResourceCollection;
+class DelegatedRendererLayer;
+
+// Only one observing layer has ownership of the DelegatedFrameProvider. Only
+// the active observer should call GetFrameDataAndRefResources(). All frames
+// provided by a single DelegatedFrameProvider must have the same size. A new
+// provider must be used for frames of a different size.
+class CC_EXPORT DelegatedFrameProvider {
+ public:
+  explicit DelegatedFrameProvider(
+      DelegatedFrameResourceCollection* resource_collection,
+      scoped_ptr<DelegatedFrameData> frame);
+  ~DelegatedFrameProvider();
+
+  void SetObserver(DelegatedRendererLayer* observer);
+  bool IsObserver(DelegatedRendererLayer* observer) const;
+
+  void SetFrameData(scoped_ptr<DelegatedFrameData> frame);
+
+  // The DelegatedFrameData returned here must be displayed in order to not
+  // lose track of damage.
+  DelegatedFrameData* GetFrameDataAndRefResources(
+      DelegatedRendererLayer* observer,
+      gfx::RectF* damage);
+
+  ReturnCallback GetReturnResourcesCallbackForImplThread();
+  void ReturnUnusedResources(const ReturnedResourceArray& unused);
+
+  gfx::Size frame_size() const { return frame_size_; }
+
+ private:
+  DelegatedFrameResourceCollection* resource_collection_;
+  DelegatedRendererLayer* frame_observer_;
+
+  scoped_ptr<DelegatedFrameData> frame_;
+  gfx::RectF damage_;
+  bool own_frame_resources_;
+
+  gfx::Size frame_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(DelegatedFrameProvider);
+};
+
+}  // namespace cc
+
+#endif  // CC_LAYERS_DELEGATED_FRAME_PROVIDER_H_