Remove the DOMToTexture feature

This relies on WebRender's frame output API, `set_output_image_handler`,
which has been removed from the latest upstream [1]. It's sad to remove
this feature, which was probably a lot of work to implement, but it
seems difficult to patch WebRender to restore this functionality.

Fixes #29936.

1. https://hg.mozilla.org/mozilla-central/rev/361521e3c52324809553c555fb066d50f023d9bf

components/script/dom/webglrenderingcontext.rs

@@ -24,7 +24,6 @@ use crate::dom::element::cors_setting_for_element;
 use crate::dom::event::{Event, EventBubbles, EventCancelable};
 use crate::dom::htmlcanvaselement::utils as canvas_utils;
 use crate::dom::htmlcanvaselement::{HTMLCanvasElement, LayoutCanvasRenderingContextHelpers};
-use crate::dom::htmliframeelement::HTMLIFrameElement;
 use crate::dom::node::{document_from_node, window_from_node, Node, NodeDamage};
 use crate::dom::promise::Promise;
 use crate::dom::vertexarrayobject::VertexAttribData;
@@ -57,11 +56,11 @@ use crate::script_runtime::JSContext as SafeJSContext;
 use backtrace::Backtrace;
 use canvas_traits::webgl::WebGLError::*;
 use canvas_traits::webgl::{
-    webgl_channel, AlphaTreatment, DOMToTextureCommand, GLContextAttributes, GLLimits, GlType,
-    Parameter, SizedDataType, TexDataType, TexFormat, TexParameter, WebGLChan, WebGLCommand,
-    WebGLCommandBacktrace, WebGLContextId, WebGLError, WebGLFramebufferBindingRequest, WebGLMsg,
-    WebGLMsgSender, WebGLProgramId, WebGLResult, WebGLSLVersion, WebGLSendResult, WebGLSender,
-    WebGLVersion, YAxisTreatment,
+    webgl_channel, AlphaTreatment, GLContextAttributes, GLLimits, GlType, Parameter, SizedDataType,
+    TexDataType, TexFormat, TexParameter, WebGLChan, WebGLCommand, WebGLCommandBacktrace,
+    WebGLContextId, WebGLError, WebGLFramebufferBindingRequest, WebGLMsg, WebGLMsgSender,
+    WebGLProgramId, WebGLResult, WebGLSLVersion, WebGLSendResult, WebGLSender, WebGLVersion,
+    YAxisTreatment,
 };
 use dom_struct::dom_struct;
 use embedder_traits::EventLoopWaker;
@@ -379,10 +378,6 @@ impl WebGLRenderingContext {
         }
     }
 
-    pub(crate) fn webgl_sender(&self) -> WebGLMessageSender {
-        self.webgl_sender.clone()
-    }
-
     pub fn context_id(&self) -> WebGLContextId {
         self.webgl_sender.context_id()
     }
@@ -4434,60 +4429,6 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
         Ok(())
     }
 
-    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.8
-    fn TexImageDOM(
-        &self,
-        target: u32,
-        level: i32,
-        internal_format: u32,
-        width: i32,
-        height: i32,
-        format: u32,
-        data_type: u32,
-        source: &HTMLIFrameElement,
-    ) -> ErrorResult {
-        // Currently DOMToTexture only supports TEXTURE_2D, RGBA, UNSIGNED_BYTE and no levels.
-        if target != constants::TEXTURE_2D ||
-            level != 0 ||
-            internal_format != constants::RGBA ||
-            format != constants::RGBA ||
-            data_type != constants::UNSIGNED_BYTE
-        {
-            return Ok(self.webgl_error(InvalidValue));
-        }
-
-        // Get bound texture
-        let texture = handle_potential_webgl_error!(
-            self,
-            self.textures
-                .active_texture_slot(constants::TEXTURE_2D, self.webgl_version())
-                .unwrap()
-                .get()
-                .ok_or(InvalidOperation),
-            return Ok(())
-        );
-
-        let pipeline_id = source.pipeline_id().ok_or(Error::InvalidState)?;
-        let document_id = self
-            .global()
-            .downcast::<Window>()
-            .ok_or(Error::InvalidState)?
-            .webrender_document();
-
-        texture.set_attached_to_dom();
-
-        let command = DOMToTextureCommand::Attach(
-            self.webgl_sender.context_id(),
-            texture.id(),
-            document_id,
-            pipeline_id.to_webrender(),
-            Size2D::new(width, height),
-        );
-        self.webgl_sender.send_dom_to_texture(command).unwrap();
-
-        Ok(())
-    }
-
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.8
     #[allow(unsafe_code)]
     fn TexSubImage2D(
@@ -5013,10 +4954,6 @@ impl WebGLMessageSender {
     pub fn send_remove(&self) -> WebGLSendResult {
         self.wake_after_send(|| self.sender.send_remove())
     }
-
-    pub fn send_dom_to_texture(&self, command: DOMToTextureCommand) -> WebGLSendResult {
-        self.wake_after_send(|| self.sender.send_dom_to_texture(command))
-    }
 }
 
 pub trait Size2DExt {

components/script/dom/webgltexture.rs

@@ -20,7 +20,7 @@ use canvas_traits::webgl::{
     webgl_channel, TexDataType, TexFormat, TexParameter, TexParameterBool, TexParameterInt,
     WebGLResult, WebGLTextureId,
 };
-use canvas_traits::webgl::{DOMToTextureCommand, WebGLCommand, WebGLError};
+use canvas_traits::webgl::{WebGLCommand, WebGLError};
 use dom_struct::dom_struct;
 use std::cell::Cell;
 use std::cmp;
@@ -62,8 +62,6 @@ pub struct WebGLTexture {
     // Store information for min and mag filters
     min_filter: Cell<u32>,
     mag_filter: Cell<u32>,
-    /// True if this texture is used for the DOMToTexture feature.
-    attached_to_dom: Cell<bool>,
     /// Framebuffer that this texture is attached to.
     attached_framebuffer: MutNullableDom<WebGLFramebuffer>,
     /// Number of immutable levels.
@@ -90,7 +88,6 @@ impl WebGLTexture {
             min_filter: Cell::new(constants::NEAREST_MIPMAP_LINEAR),
             mag_filter: Cell::new(constants::LINEAR),
             image_info_array: DomRefCell::new([None; MAX_LEVEL_COUNT * MAX_FACE_COUNT]),
-            attached_to_dom: Cell::new(false),
             attached_framebuffer: Default::default(),
         }
     }
@@ -224,12 +221,6 @@ impl WebGLTexture {
         if !self.is_deleted.get() {
             self.is_deleted.set(true);
             let context = self.upcast::<WebGLObject>().context();
-            // Notify WR to release the frame output when using DOMToTexture feature
-            if self.attached_to_dom.get() {
-                let _ = context
-                    .webgl_sender()
-                    .send_dom_to_texture(DOMToTextureCommand::Detach(self.id));
-            }
 
             /*
             If a texture object is deleted while its image is attached to one or more attachment
@@ -469,10 +460,6 @@ impl WebGLTexture {
         self.image_info_at_face(0, self.base_mipmap_level)
     }
 
-    pub fn set_attached_to_dom(&self) {
-        self.attached_to_dom.set(true);
-    }
-
     pub fn attach_to_framebuffer(&self, fb: &WebGLFramebuffer) {
         self.attached_framebuffer.set(Some(fb));
     }

components/script/dom/webidls/WebGLRenderingContext.webidl

@@ -680,16 +680,9 @@ interface mixin WebGLRenderingContextOverloads
     undefined uniformMatrix4fv(WebGLUniformLocation? location, GLboolean transpose, Float32List value);
 };
 
-interface mixin WebGLRenderingContextExtensions {
-    [Throws, Pref="dom.webgl.dom_to_texture.enabled"]
-    undefined texImageDOM(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height,
-                     GLenum format, GLenum type, HTMLIFrameElement source); // May throw DOMException
-};
-
 [Exposed=(Window)]
 interface WebGLRenderingContext
 {
 };
 WebGLRenderingContext includes WebGLRenderingContextBase;
 WebGLRenderingContext includes WebGLRenderingContextOverloads;
-WebGLRenderingContext includes WebGLRenderingContextExtensions;