Mac Overlays: Add sandwich strategy

cc/output/overlay_strategy_sandwich.h

+// Copyright 2015 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_OUTPUT_OVERLAY_STRATEGY_SANDWICH_H_
+#define CC_OUTPUT_OVERLAY_STRATEGY_SANDWICH_H_
+
+#include "cc/output/overlay_strategy_common.h"
+
+namespace cc {
+
+// The sandwich strategy looks for a video quad without regard to quads above
+// it. The video is "overlaid" on top of the scene, and then the non-empty
+// parts of the scene are "overlaid" on top of the video. This is only valid
+// for overlay contents that are fully opaque.
+class CC_EXPORT OverlayStrategySandwich : public OverlayStrategyCommonDelegate {
+ public:
+  OverlayStrategySandwich() {}
+  ~OverlayStrategySandwich() override;
+
+  bool TryOverlay(OverlayCandidateValidator* capability_checker,
+                  RenderPassList* render_passes_in_draw_order,
+                  OverlayCandidateList* candidate_list,
+                  const OverlayCandidate& candidate,
+                  QuadList::Iterator candidate_iterator,
+                  float device_scale_factor) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(OverlayStrategySandwich);
+};
+
+}  // namespace cc
+
+#endif  // CC_OUTPUT_OVERLAY_STRATEGY_SANDWICH_H_