Add DCLayerOverlayProcessor and supporting DCLayer structures.

components/display_compositor/compositor_overlay_candidate_validator_mac.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 COMPONENTS_DISPLAY_COMPOSITOR_COMPOSITOR_OVERLAY_CANDIDATE_VALIDATOR_MAC_H_
 #define COMPONENTS_DISPLAY_COMPOSITOR_COMPOSITOR_OVERLAY_CANDIDATE_VALIDATOR_MAC_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "components/display_compositor/compositor_overlay_candidate_validator.h"
 #include "components/display_compositor/display_compositor_export.h"
 
 namespace display_compositor {
 
 class DISPLAY_COMPOSITOR_EXPORT CompositorOverlayCandidateValidatorMac
     : public CompositorOverlayCandidateValidator {
  public:
   explicit CompositorOverlayCandidateValidatorMac(bool ca_layer_disabled);
   ~CompositorOverlayCandidateValidatorMac() override;
 
   // cc::OverlayCandidateValidator implementation.
   void GetStrategies(cc::OverlayProcessor::StrategyList* strategies) override;
   bool AllowCALayerOverlays() override;
+  bool AllowDCLayerOverlays() override;
   void CheckOverlaySupport(cc::OverlayCandidateList* surfaces) override;
 
   // CompositorOverlayCandidateValidator implementation.
   void SetSoftwareMirrorMode(bool enabled) override;
 
  private:
   bool software_mirror_active_;
   const bool ca_layer_disabled_;
 
   DISALLOW_COPY_AND_ASSIGN(CompositorOverlayCandidateValidatorMac);
 };
 
 }  // namespace display_compositor
 
 #endif  // COMPONENTS_DISPLAY_COMPOSITOR_COMPOSITOR_OVERLAY_CANDIDATE_VALIDATOR_MAC_H_