GpuCompositorFrameSink implements cc::mojom::DisplayPrivate

cc/ipc/display_compositor.mojom

 // 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.
 
 module cc.mojom;
 
 import "cc/ipc/frame_sink_id.mojom";
 import "cc/ipc/mojo_compositor_frame_sink.mojom";
 import "cc/ipc/surface_id.mojom";
 import "cc/ipc/surface_sequence.mojom";
 import "gpu/ipc/common/surface_handle.mojom";
+import "mojo/common/time.mojom";
 import "ui/gfx/geometry/mojo/geometry.mojom";
+import "ui/gfx/mojo/color_space.mojom";
+
+// See cc/surfaces/display.h

[rjkroege, 2016/12/20 00:51:51]

I'd like the .mojom to have more detailed documentation. display.h (at least the
version currently used for code search) doesn't separate the private from the
public interface so perhaps this could have more stand-alone commentary.

Also, what's the reasoning for the name variance between Display::SetColorSpace,
Display::SetVisible, Display::Resize and these methods?

[Alex Z., 2016/12/20 15:36:52]

Currently ash talks to cc::Display through ContextFactoryPrivate. This mojo
interface would eventually replace ContextFactoryPrivate or would be used by it.
Besides, this is implemented by GpuCompositorFrameSink instead of cc::Display.
Hence, I think it's more appropriate to use the names in ContextFactoryPrivate
instead of the method names in cc::Display.

[Alex Z., 2016/12/20 15:49:11]

Done.

[rjkroege, 2016/12/20 19:18:08]

Given the above, it's not appropriate to reference cc::Display to document these
methods. Instead, you should at least refer to ContextFactoryPrivate yes?

[Alex Z., 2016/12/20 19:55:54]

Done.

+interface DisplayPrivate {
+  SetDisplayVisible(bool visible);
+  ResizeDisplay(gfx.mojom.Size size_in_pixel);
+  SetDisplayColorSpace(gfx.mojom.ColorSpace color_space);
+  SetOutputIsSecure(bool secure);
+};
 
 // The DisplayCompositor interface is a privileged interface that allows
 // the display compositor host (browser or window server) to create
 // CompositorFrameSinks. Clients acquire a CompositorFrameSink connection
 // through the display compositor host. Clients request a
 // MojoCompositorFrameSink interface, and implement a
 // MojoCompositorFrameSinkClient interface. The display compositor host
 // holds one or more root CompositorFrameSinks that are tied to a valid
 // |surface_handle|. All other CompositorFrameSinks are offscreen. FrameSinkIds
 // are fixed for a given client and are determined ahead of time. Thus, a client
 // will typically simply request a CompositorFrameSink from the display
 // compositor host which will forward the request to the display compositor.
 interface DisplayCompositor {
+  // Create a CompositorFrameSink for a privileged client (e.g. WindowServer).
+  // This is only used by privileged clients. The client can call methods that
+  // talks to the cc::Display (e.g. ResizeDisplay(), SetDisplayVisible(), etc)
   CreateDisplayCompositorFrameSink(
       cc.mojom.FrameSinkId frame_sink_id,
       gpu.mojom.SurfaceHandle widget,
       cc.mojom.MojoCompositorFrameSink& compositor_frame_sink,
       cc.mojom.MojoCompositorFrameSinkPrivate& compositor_frame_sink_private,
-      cc.mojom.MojoCompositorFrameSinkClient compositor_frame_sink_client);
+      cc.mojom.MojoCompositorFrameSinkClient compositor_frame_sink_client,
+      DisplayPrivate& display_private);
 
+  // CreateOffscreenCompositorFrameSink is used by non-privileged clients.
+  // An off screen CompositorFrameSink only submits frames to a buffer instead
+  // of a display.
   CreateOffscreenCompositorFrameSink(
       cc.mojom.FrameSinkId frame_sink_id,
       cc.mojom.MojoCompositorFrameSink& compositor_frame_sink,
       cc.mojom.MojoCompositorFrameSinkPrivate& compositor_frame_sink_private,
       cc.mojom.MojoCompositorFrameSinkClient compositor_frame_sink_client);
 };
 
 // The DisplayCompositorClient interface is implemented by the Display
 // Compositor Host, a stable, and privileged peer service to the display
 // compositor. The display compositor host is either the browser process in
 // Chrome or the window server process.
 interface DisplayCompositorClient {
   // Called by the display compostor when it is created. Provides the top level
   // root surface id that should reference display roots. This will always be
   // the first message sent.
   OnDisplayCompositorCreated(cc.mojom.SurfaceId root_surface_id);
 
   // Called by the display compositor immediately upon receiving a
   // CompositorFrame with a new SurfaceId for the first time.
   OnSurfaceCreated(cc.mojom.SurfaceId surface_id,
                    gfx.mojom.Size frame_size,
                    float device_scale_factor);
 };