Add underlays and split off common overlay functionality

cc/output/overlay_strategy_underlay.h

Index: cc/output/overlay_strategy_underlay.h
diff --git a/cc/output/overlay_strategy_underlay.h b/cc/output/overlay_strategy_underlay.h
new file mode 100644
index 0000000000000000000000000000000000000000..4bcc2cbfe8adda750af29cdd258aeaa2dc325a4f
--- /dev/null
+++ b/cc/output/overlay_strategy_underlay.h
@@ -0,0 +1,40 @@
+// Copyright 2014 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_UNDERLAY_H_
+#define CC_OUTPUT_OVERLAY_STRATEGY_UNDERLAY_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "cc/base/cc_export.h"
+#include "cc/output/overlay_candidate.h"
+#include "cc/output/overlay_processor.h"
+#include "cc/output/overlay_strategy_common.h"
+#include "cc/quads/render_pass.h"
+
+namespace cc {
+class OverlayCandidateValidator;
+class StreamVideoDrawQuad;
+class TextureDrawQuad;
+
+// The underlay strategy looks for a video quad without regard to quads above
+// it. The video is "underlaid" through the same mechanism as the video hole -
+// a black transparent quad blended normally.
+class CC_EXPORT OverlayStrategyUnderlay : public OverlayStrategyCommon {
+ public:
+  OverlayStrategyUnderlay(OverlayCandidateValidator* capability_checker,
+                          ResourceProvider* resource_provider);
+  bool Attempt(RenderPassList* render_passes_in_draw_order,
+               OverlayCandidateList* candidate_list) override;
+
+ private:
+  bool IsOverlayQuad(const DrawQuad* draw_quad);
+
+  OverlayCandidateValidator* capability_checker_;
+  DISALLOW_COPY_AND_ASSIGN(OverlayStrategyUnderlay);
+};
+
+}  // namespace cc
+
+#endif  // CC_OUTPUT_OVERLAY_STRATEGY_UNDERLAY_H_