Mac: Add detection for low power video compatible frames

ui/accelerated_widget_mac/ca_renderer_layer_tree.h

 // Copyright 2016 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 UI_ACCELERATED_WIDGET_MAC_CA_RENDERER_LAYER_TREE_H_
 #define UI_ACCELERATED_WIDGET_MAC_CA_RENDERER_LAYER_TREE_H_
 
 #include <IOSurface/IOSurface.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 41 matching lines @@
 
   // Create a CALayer tree for the scheduled layers, and set |superlayer| to
   // have only this tree as its sublayers. If |old_tree| is non-null, then try
   // to re-use the CALayers of |old_tree| as much as possible. |old_tree| will
   // be destroyed at the end of the function, and any CALayers in it which were
   // not re-used by |this| will be removed from the CALayer hierarchy.
   void CommitScheduledCALayers(CALayer* superlayer,
                                std::unique_ptr<CARendererLayerTree> old_tree,
                                float scale_factor);
 
+  // Check to see if the CALayer tree can be represented entirely by a video
+  // layer on a black background. If so, then set |fullscreen_low_power_layer|
+  // to draw this content and return true. Otherwise return false. This is to
+  // be called after committing scheduled CALayers.
+  bool CommitFullscreenLowPowerLayer(
+      AVSampleBufferDisplayLayer* fullscreen_low_power_layer);
+
  private:
   struct RootLayer;
   struct ClipAndSortingLayer;
   struct TransformLayer;
   struct ContentLayer;
 
   struct RootLayer {
     RootLayer();
 
     // This will remove |ca_layer| from its superlayer, if |ca_layer| is
@@ skipping 132 matching lines @@
   float scale_factor_ = 1;
   bool has_committed_ = false;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CARendererLayerTree);
 };
 
 }  // namespace ui
 
 #endif  // UI_ACCELERATED_WIDGET_MAC_CA_LAYER_TREE_MAC_H_