Move logic from ImageTransportSurfaceOverlayMac into ui/

ui/accelerated_widget_mac/ca_layer_tree_host.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_LAYER_TREE_HOST_H_
+#define UI_ACCELERATED_WIDGET_MAC_CA_LAYER_TREE_HOST_H_
+
+#include "ui/accelerated_widget_mac/accelerated_widget_mac_export.h"
+#include "ui/accelerated_widget_mac/ca_layer_partial_damage_tree_mac.h"
+#include "ui/accelerated_widget_mac/ca_layer_tree_mac.h"
+
+namespace ui {
+
+// A structure that holds CALayer tree for web content from the compositor. The

[erikchen, 2016/04/25 20:05:36]

Maybe: A structure that holds a tree of CALayers that represents web contents
from a RenderWidgetHostViewMac, after the contents has been processed by the
compositor....

[ccameron, 2016/04/26 22:36:40]

I changed it to "composited content", because a RWHVMac may not be involved for
browser-side composited stuff.

+// CALayer tree may consist of a CALayerPartialDamageTree if the OpenGL renderer
+// is being used, or a CALayerTree if the CoreAnimation renderer is being used.
+class ACCELERATED_WIDGET_MAC_EXPORT CALayerTreeHost {

[erikchen, 2016/04/25 20:05:36]

disallow copy and assign?

Also, I prefer that you don't use the word *Host*, since we tend to use that to
mean an object responsible for managing another process. CALayerTreeCoordinator
sounds fine.

[ccameron, 2016/04/26 22:36:40]

Done.
Replaced Host with Coordinator (especially now that we have two different
structures that are called XLayerTree, and this coordinates switching between
them).

+ public:
+  CALayerTreeHost(bool allow_remote_layers);

[erikchen, 2016/04/25 20:05:36]

explicit

It looks like the public interface of this class is highly dependent on
allow_remote_layers. At the very least, you should organize the public interface
into 3 sections:

1. Methods that can always be called.
2. Methods that should only be called if allow_remote_layers=true
3. Methods that should only be called if allow_remote_layers=false.

The implementations of the methods in (2) and (3) should have DCHECKs.

[ccameron, 2016/04/26 22:36:40]

Done
The structure of the file is
- Stuff that is called before a frame is generated
- Stuff that is called to generate content in a frame
(SetPendingBackbuffer/GetPendingCALayerTree)
- Stuff to complete the frame (CommitPendingTreesToCA)
- Stuff to display the completed frame (GetRootCALayer and
GetFrontbufferIOSurface).

I've added some DCHECKs and comments about remote layers. In the near future, we
should be able to get rid of the remote layer stuff (cause this will be in the
browser process).

+  ~CALayerTreeHost();
+
+  // Set the composited frame's size.
+  void Resize(const gfx::Size& pixel_size, float scale_factor);
+
+  // Set the OpenGL backbuffer to which the pending frame was rendered. This is
+  // used to draw frames created by the OpenGL renderer.
+  bool SetPendingBackbuffer(base::ScopedCFTypeRef<IOSurfaceRef> backbuffer);
+
+  // The the CALayerTree for the pending frame. This is used to construct the
+  // CALayer tree for the CoreAnimation renderer.
+  CALayerTree* GetPendingCALayerTree();
+
+  // Commit the pending frame's OpenGL backbuffer or CALayer tree to be
+  // attached to the root CALayer.
+  void CommitPendingTreesToCA(const gfx::Rect& pixel_damage_rect);
+
+  // Get the root CALayer to display the current frame.
+  CALayer* GetRootCALayer() const { return root_ca_layer_.get(); }
+
+  // Get the current frame's OpenGL backbuffer IOSurface. This is only needed
+  // when not using remote layers.
+  IOSurfaceRef GetFrontbufferIOSurface();
+
+ private:
+  bool allow_remote_layers_ = true;
+  gfx::Size pixel_size_;
+  float scale_factor_ = 1;
+
+  base::scoped_nsobject<CALayer> root_ca_layer_;
+
+  // Frame that has been scheduled, but has not had a subsequent commit call
+  // made yet.
+  std::unique_ptr<CALayerPartialDamageTree> pending_partial_damage_tree_;
+  std::unique_ptr<CALayerTree> pending_ca_layer_tree_;
+
+  // Frame that is currently being displayed on the screen.
+  std::unique_ptr<CALayerPartialDamageTree> current_partial_damage_tree_;
+  std::unique_ptr<CALayerTree> current_ca_layer_tree_;
+};
+
+}  // namespace ui
+
+#endif  // UI_ACCELERATED_WIDGET_MAC_CA_LAYER_TREE_HOST_H_