Mac: Use AVSampleBufferDisplayLayer for 4:2:0 surfaces

content/common/gpu/ca_layer_tree_mac.h

Index: content/common/gpu/ca_layer_tree_mac.h
diff --git a/content/common/gpu/ca_layer_tree_mac.h b/content/common/gpu/ca_layer_tree_mac.h
index 0840b31cd6dcfc1991d5c6462b97968ceeefbb42..962f6cac85c0d5d6d0cd909d6357e25d00773b08 100644
--- a/content/common/gpu/ca_layer_tree_mac.h
+++ b/content/common/gpu/ca_layer_tree_mac.h
@@ -18,6 +18,8 @@
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/transform.h"
 
+@class AVSampleBufferDisplayLayer;
+
 namespace content {
 
 // The CALayerTree will construct a hierarchy of CALayers from a linear list,
@@ -174,6 +176,11 @@ class CONTENT_EXPORT CALayerTree {
     float opacity = 1;
     base::scoped_nsobject<CALayer> ca_layer;
 
+    // If this layer's contents can be represented as an
+    // AVSampleBufferDisplayLayer, then |ca_layer| will point to |av_layer|.
+    base::scoped_nsobject<AVSampleBufferDisplayLayer> av_layer;
+    bool use_av_layer = false;
+
    private:
     DISALLOW_COPY_AND_ASSIGN(ContentLayer);
   };