GpuCompositorFrameSink implements cc::mojom::DisplayPrivate

cc/ipc/display_compositor.mojom

Index: cc/ipc/display_compositor.mojom
diff --git a/cc/ipc/display_compositor.mojom b/cc/ipc/display_compositor.mojom
index 06abdbd55d3d1ec4b2b64cde7f43aa327679764b..a38e29a25235dbdec2efdadc1c248757831009f7 100644
--- a/cc/ipc/display_compositor.mojom
+++ b/cc/ipc/display_compositor.mojom
@@ -9,7 +9,17 @@ 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
@@ -23,13 +33,20 @@ import "ui/gfx/geometry/mojo/geometry.mojom";
 // 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,