exo: no-roundtrip dmabuf import

components/exo/wayland/server.cc

Index: components/exo/wayland/server.cc
diff --git a/components/exo/wayland/server.cc b/components/exo/wayland/server.cc
index 0d27ff60d55be550aef2945f2011f1ee3685a9be..aae71272ec346aa50273e3f760705016722064c4 100644
--- a/components/exo/wayland/server.cc
+++ b/components/exo/wayland/server.cc
@@ -646,12 +646,13 @@ void linux_buffer_params_add(wl_client* client,
   }
 }
 
-void linux_buffer_params_create(wl_client* client,
-                                wl_resource* resource,
-                                int32_t width,
-                                int32_t height,
-                                uint32_t format,
-                                uint32_t flags) {
+void linux_buffer_params_create_impl(wl_client* client,

[reveman, 2017/04/28 17:21:24]

I think the code will be easier to read if you didn't add this _impl function
but instead some code duplication in immed and non-immed functions. if the code
duplication is too great then maybe add a utility function or two.

+                                     wl_resource* resource,
+                                     uint32_t buffer_id,
+                                     int32_t width,
+                                     int32_t height,
+                                     uint32_t format,
+                                     uint32_t flags) {
   if (width <= 0 || height <= 0) {
     wl_resource_post_error(resource,
                            ZWP_LINUX_BUFFER_PARAMS_V1_ERROR_INVALID_DIMENSIONS,
@@ -712,25 +713,57 @@ void linux_buffer_params_create(wl_client* client,
           gfx::Size(width, height), supported_format->buffer_format, planes,
           std::move(fds));
   if (!buffer) {
-    zwp_linux_buffer_params_v1_send_failed(resource);
-    return;
+    // buffer_id != 0 indicates a create_immed request. on import failure
+    // in that case, the protocol allows us to raise a fatal error from
+    // zwp_linux_dmabuf_v1 version 2+.
+    if (buffer_id == 0)
+      zwp_linux_buffer_params_v1_send_failed(resource);
+    else {
+      wl_resource_post_error(resource,
+                             ZWP_LINUX_BUFFER_PARAMS_V1_ERROR_INVALID_WL_BUFFER,
+                             "dmabuf import failed");
+      return;
+    }
   }
 
   wl_resource* buffer_resource =
-      wl_resource_create(client, &wl_buffer_interface, 1, 0);
+      wl_resource_create(client, &wl_buffer_interface, 1, buffer_id);
 
   buffer->set_release_callback(base::Bind(&HandleBufferReleaseCallback,
                                           base::Unretained(buffer_resource)));
 
   SetImplementation(buffer_resource, &buffer_implementation, std::move(buffer));
 
-  zwp_linux_buffer_params_v1_send_created(resource, buffer_resource);
+  // for a create_immed request, no event is triggered.
+  if (buffer_id == 0)
+    zwp_linux_buffer_params_v1_send_created(resource, buffer_resource);
+}
+
+void linux_buffer_params_create(wl_client* client,
+                                wl_resource* resource,
+                                int32_t width,
+                                int32_t height,
+                                uint32_t format,
+                                uint32_t flags) {
+  linux_buffer_params_create_impl(client, resource, 0, width, height, format,
+                                  flags);
+}
+
+void linux_buffer_params_create_immed(wl_client* client,
+                                      wl_resource* resource,
+                                      uint32_t buffer_id,
+                                      int32_t width,
+                                      int32_t height,
+                                      uint32_t format,
+                                      uint32_t flags) {
+  linux_buffer_params_create_impl(client, resource, buffer_id, width, height,
+                                  format, flags);
 }
 
 const struct zwp_linux_buffer_params_v1_interface
-    linux_buffer_params_implementation = {linux_buffer_params_destroy,
-                                          linux_buffer_params_add,
-                                          linux_buffer_params_create};
+    linux_buffer_params_implementation = {
+        linux_buffer_params_destroy, linux_buffer_params_add,
+        linux_buffer_params_create, linux_buffer_params_create_immed};
 
 ////////////////////////////////////////////////////////////////////////////////
 // linux_dmabuf_interface:
@@ -746,7 +779,7 @@ void linux_dmabuf_create_params(wl_client* client,
       base::MakeUnique<LinuxBufferParams>(GetUserDataAs<Display>(resource));
 
   wl_resource* linux_buffer_params_resource =
-      wl_resource_create(client, &zwp_linux_buffer_params_v1_interface, 1, id);
+      wl_resource_create(client, &zwp_linux_buffer_params_v1_interface, 2, id);
 
   SetImplementation(linux_buffer_params_resource,
                     &linux_buffer_params_implementation,
@@ -761,7 +794,7 @@ void bind_linux_dmabuf(wl_client* client,
                        uint32_t version,
                        uint32_t id) {
   wl_resource* resource =
-      wl_resource_create(client, &zwp_linux_dmabuf_v1_interface, 1, id);
+      wl_resource_create(client, &zwp_linux_dmabuf_v1_interface, version, id);
 
   wl_resource_set_implementation(resource, &linux_dmabuf_implementation, data,
                                  nullptr);
@@ -3853,7 +3886,7 @@ Server::Server(Display* display)
 #if defined(USE_OZONE)
   wl_global_create(wl_display_.get(), &wl_drm_interface, drm_version, display_,
                    bind_drm);
-  wl_global_create(wl_display_.get(), &zwp_linux_dmabuf_v1_interface, 1,
+  wl_global_create(wl_display_.get(), &zwp_linux_dmabuf_v1_interface, 2,
                    display_, bind_linux_dmabuf);
 #endif
   wl_global_create(wl_display_.get(), &wl_subcompositor_interface, 1, display_,