Remove Constellation::child_processes.

Fixes https://github.com/servo/servo/issues/11459.

components/constellation/constellation.rs

@@ -35,7 +35,7 @@ use net_traits::image_cache_thread::ImageCacheThread;
 use net_traits::pub_domains::reg_suffix;
 use net_traits::storage_thread::{StorageThreadMsg, StorageType};
 use offscreen_gl_context::{GLContextAttributes, GLLimits};
-use pipeline::{ChildProcess, InitialPipelineState, Pipeline};
+use pipeline::{InitialPipelineState, Pipeline};
 use profile_traits::mem;
 use profile_traits::time;
 use rand::{Rng, SeedableRng, StdRng, random};
@@ -175,10 +175,6 @@ pub struct Constellation<Message, LTF, STF> {
 
     scheduler_chan: IpcSender<TimerEventRequest>,
 
-    /// A list of child content processes.
-    #[cfg_attr(target_os = "windows", allow(dead_code))]
-    child_processes: Vec<ChildProcess>,
-
     /// Document states for loaded pipelines (used only when writing screenshots).
     document_states: HashMap<PipelineId, DocumentState>,
 
@@ -558,7 +554,6 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 phantom: PhantomData,
                 webdriver: WebDriverData::new(),
                 scheduler_chan: TimerScheduler::start(),
-                child_processes: Vec::new(),
                 document_states: HashMap::new(),
                 webrender_api_sender: state.webrender_api_sender,
                 shutting_down: false,
@@ -679,15 +674,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             is_private: is_private,
         });
 
-        let (pipeline, child_process) = match result {
+        let pipeline = match result {
             Ok(result) => result,
             Err(e) => return self.handle_send_error(pipeline_id, e),
         };
 
-        if let Some(child_process) = child_process {
-            self.child_processes.push(child_process);
-        }
-
         if let Some(host) = host {
             self.script_channels.entry(top_level_frame_id)
                 .or_insert_with(HashMap::new)

components/constellation/pipeline.rs

@@ -134,15 +134,14 @@ pub struct InitialPipelineState {
 impl Pipeline {
     /// Starts a paint thread, layout thread, and possibly a script thread, in
     /// a new process if requested.
-    pub fn spawn<Message, LTF, STF>(state: InitialPipelineState)
+    pub fn spawn<Message, LTF, STF>(state: InitialPipelineState) -> Result<Pipeline, IOError>
-                                    -> Result<(Pipeline, Option<ChildProcess>), IOError>
         where LTF: LayoutThreadFactory<Message=Message>,
               STF: ScriptThreadFactory<Message=Message>
     {
         // Note: we allow channel creation to panic, since recovering from this
         // probably requires a general low-memory strategy.
         let (pipeline_chan, pipeline_port) = ipc::channel()
-            .expect("Pipeline main chan");;
+            .expect("Pipeline main chan");
 
         let (layout_content_process_shutdown_chan, layout_content_process_shutdown_port) =
             ipc::channel().expect("Pipeline layout content shutdown chan");
@@ -180,7 +179,6 @@ impl Pipeline {
             }
         };
 
-        let mut child_process = None;
         if let Some((script_port, pipeline_port)) = content_ports {
             // Route messages coming from content to devtools as appropriate.
             let script_to_devtools_chan = state.devtools_chan.as_ref().map(|devtools_chan| {
@@ -236,13 +234,13 @@ impl Pipeline {
             //
             // Yes, that's all there is to it!
             if opts::multiprocess() {
-                child_process = Some(try!(unprivileged_pipeline_content.spawn_multiprocess()));
+                let _ = try!(unprivileged_pipeline_content.spawn_multiprocess());
             } else {
                 unprivileged_pipeline_content.start_all::<Message, LTF, STF>(false);
             }
         }
 
-        let pipeline = Pipeline::new(state.id,
+        Ok(Pipeline::new(state.id,
                          state.frame_id,
                          state.parent_info,
                          script_chan,
@@ -251,9 +249,7 @@ impl Pipeline {
                          state.is_private,
                          state.load_data.url,
                          state.window_size,
-                                     state.prev_visibility.unwrap_or(true));
+                         state.prev_visibility.unwrap_or(true)))
-
-        Ok((pipeline, child_process))
     }
 
     /// Creates a new `Pipeline`, after the script and layout threads have been