Add underlays and split off common overlay functionality

cc/output/overlay_strategy_common.h

Index: cc/output/overlay_strategy_common.h
diff --git a/cc/output/overlay_strategy_single_on_top.h b/cc/output/overlay_strategy_common.h
similarity index 57%
copy from cc/output/overlay_strategy_single_on_top.h
copy to cc/output/overlay_strategy_common.h
index a3fec0a66e38a4d9019ab193c7eb445bcee7170f..515a106e78201199660a22f3ac40fd04dc80027c 100644
--- a/cc/output/overlay_strategy_single_on_top.h
+++ b/cc/output/overlay_strategy_common.h
@@ -1,31 +1,27 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
+// 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_SINGLE_ON_TOP_H_
-#define CC_OUTPUT_OVERLAY_STRATEGY_SINGLE_ON_TOP_H_
+#ifndef CC_OUTPUT_OVERLAY_STRATEGY_COMMON_H_
+#define CC_OUTPUT_OVERLAY_STRATEGY_COMMON_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/quads/render_pass.h"
 
 namespace cc {
 class OverlayCandidateValidator;
 class StreamVideoDrawQuad;
 class TextureDrawQuad;
+class OverlayCandidate;
 
-class CC_EXPORT OverlayStrategySingleOnTop : public OverlayProcessor::Strategy {
+class CC_EXPORT OverlayStrategyCommon : public OverlayProcessor::Strategy {
  public:
-  OverlayStrategySingleOnTop(OverlayCandidateValidator* capability_checker,
-                             ResourceProvider* resource_provider);
-  bool Attempt(RenderPassList* render_passes_in_draw_order,
-               OverlayCandidateList* candidate_list) override;
+  OverlayStrategyCommon(OverlayCandidateValidator* capability_checker,
+                        ResourceProvider* resource_provider);
+  ~OverlayStrategyCommon() override;
 
- private:
-  bool IsOverlayQuad(const DrawQuad* draw_quad);
+ protected:
   bool GetCandidateQuadInfo(const DrawQuad& draw_quad,
                             OverlayCandidate* quad_info);
 
@@ -33,6 +29,10 @@ class CC_EXPORT OverlayStrategySingleOnTop : public OverlayProcessor::Strategy {
   // an overlay.
   bool IsInvisibleQuad(const DrawQuad* draw_quad);
 
+  // Returns true if |draw_quad| is of a known quad type and contains an
+  // overlayable resource.
+  bool IsOverlayQuad(const DrawQuad* draw_quad);
+
   bool GetTextureQuadInfo(const TextureDrawQuad& quad,
                           OverlayCandidate* quad_info);
   bool GetVideoQuadInfo(const StreamVideoDrawQuad& quad,
@@ -40,9 +40,10 @@ class CC_EXPORT OverlayStrategySingleOnTop : public OverlayProcessor::Strategy {
 
   OverlayCandidateValidator* capability_checker_;
   ResourceProvider* resource_provider_;
-  DISALLOW_COPY_AND_ASSIGN(OverlayStrategySingleOnTop);
-};
 
+ private:
+  DISALLOW_COPY_AND_ASSIGN(OverlayStrategyCommon);
+};
 }  // namespace cc
 
-#endif  // CC_OUTPUT_OVERLAY_STRATEGY_SINGLE_ON_TOP_H_
+#endif  // CC_OUTPUT_OVERLAY_STRATEGY_COMMON_H_