Introduce Display Compositor mojo interface. Use InProcessContextProvider.

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 c3ae783e6def4e62ec85589f59d0fd022b7503e4..2e52e761d8cc60773347cdb1c5fe81f397c967fb 100644
--- a/cc/ipc/display_compositor.mojom
+++ b/cc/ipc/display_compositor.mojom
@@ -4,9 +4,31 @@
 
 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 "ui/gfx/geometry/mojo/geometry.mojom";
 
+// The DisplayCompositor interface is a privileged interface that allows
+// the display compositor host (browser or window server) to create
+// CompositorFrameSinks.
+interface DisplayCompositor {
+  CreateCompositorFrameSink(
+      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);
+
+   // TODO(fsamuel): Remove these once we switch to surface references.
+   AddSurfaceReference(cc.mojom.SurfaceId surface_id,
+                       cc.mojom.SurfaceSequence sequence);
+   ReturnSurfaceReferences(cc.mojom.FrameSinkId frame_sink_id,
+                           array<uint32> sequences);
+};
+
 // 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