Move non-gfx things out of gfx_traits and create a base crate (#32296)

For a long time, `gfx_traits` has held a lot of things unrelated to graphics
and also unrelated to the `gfx` crate (which is mostly about fonts).
This is a cleanup which does a few things:

1. Move non `gfx` crate things out of `gfx_traits`. This is important in
   order to prevent dependency cycles with a different integration between
   layout, script, and fonts.
2. Rename the `msg` crate to `base`. It didn't really contain anything
   to do with messages and instead mostly holds ids, which are used
   across many different crates in Servo. This new crate will hold the
   *rare* data types that are widely used.

Details:

 - All BackgroundHangMonitor-related things from base to a new
   `background_hang_monitor_api` crate.
 - Moved `TraversalDirection` to `script_traits`
 - Moved `Epoch`-related things from `gfx_traits` to `base`.
 - Moved `PrintTree` to base. This should be widely useful in Servo.
 - Moved `WebrenderApi` from `base` to `webrender_traits` and renamed it
   to `WebRenderFontApi`.

components/devtools/Cargo.toml

@@ -14,6 +14,7 @@ path = "lib.rs"
 chrono = "0.4"
 
 [dependencies]
+base = { workspace = true }
 chrono = "0.4"
 crossbeam-channel = { workspace = true }
 devtools_traits = { workspace = true }
@@ -22,7 +23,6 @@ headers = { workspace = true }
 http = { workspace = true }
 ipc-channel = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 servo_config = { path = "../config" }

components/devtools/actors/browsing_context.rs

@@ -10,10 +10,10 @@ use std::cell::{Cell, RefCell};
 use std::collections::HashMap;
 use std::net::TcpStream;
 
+use base::id::{BrowsingContextId, PipelineId};
 use devtools_traits::DevtoolScriptControlMsg::{self, WantsLiveNotifications};
 use devtools_traits::{DevtoolsPageInfo, NavigationState};
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use serde::Serialize;
 use serde_json::{Map, Value};
 

components/devtools/actors/console.rs

@@ -11,6 +11,7 @@ use std::collections::HashMap;
 use std::net::TcpStream;
 use std::time::{SystemTime, UNIX_EPOCH};
 
+use base::id::TEST_PIPELINE_ID;
 use devtools_traits::EvaluateJSReply::{
     ActorValue, BooleanValue, NullValue, NumberValue, StringValue, VoidValue,
 };
@@ -20,7 +21,6 @@ use devtools_traits::{
 };
 use ipc_channel::ipc::{self, IpcSender};
 use log::debug;
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use serde::Serialize;
 use serde_json::{self, Map, Number, Value};
 use uuid::Uuid;

components/devtools/actors/framerate.rs

@@ -5,9 +5,9 @@
 use std::mem;
 use std::net::TcpStream;
 
+use base::id::PipelineId;
 use devtools_traits::DevtoolScriptControlMsg;
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::PipelineId;
 use serde_json::{Map, Value};
 
 use crate::actor::{Actor, ActorMessageStatus, ActorRegistry};

components/devtools/actors/inspector.rs

@@ -7,12 +7,12 @@
 use std::cell::RefCell;
 use std::net::TcpStream;
 
+use base::id::PipelineId;
 use devtools_traits::DevtoolScriptControlMsg::{
     GetChildren, GetDocumentElement, GetLayout, GetRootNode, ModifyAttribute,
 };
 use devtools_traits::{ComputedNodeLayout, DevtoolScriptControlMsg, NodeInfo};
 use ipc_channel::ipc::{self, IpcSender};
-use msg::constellation_msg::PipelineId;
 use serde::Serialize;
 use serde_json::{self, Map, Value};
 

components/devtools/actors/timeline.rs

@@ -9,10 +9,10 @@ use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
 
+use base::id::PipelineId;
 use devtools_traits::DevtoolScriptControlMsg::{DropTimelineMarkers, SetTimelineMarkers};
 use devtools_traits::{DevtoolScriptControlMsg, PreciseTime, TimelineMarker, TimelineMarkerType};
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
-use msg::constellation_msg::PipelineId;
 use serde::{Serialize, Serializer};
 use serde_json::{Map, Value};
 

components/devtools/actors/worker.rs

@@ -6,10 +6,10 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use std::net::TcpStream;
 
+use base::id::TEST_PIPELINE_ID;
 use devtools_traits::DevtoolScriptControlMsg::WantsLiveNotifications;
 use devtools_traits::{DevtoolScriptControlMsg, WorkerId};
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use serde::Serialize;
 use serde_json::{Map, Value};
 use servo_url::ServoUrl;

components/devtools/lib.rs

@@ -20,6 +20,7 @@ use std::net::{Shutdown, TcpListener, TcpStream};
 use std::sync::{Arc, Mutex};
 use std::thread;
 
+use base::id::{BrowsingContextId, PipelineId};
 use crossbeam_channel::{unbounded, Receiver, Sender};
 use devtools_traits::{
     ChromeToDevtoolsControlMsg, ConsoleMessage, DevtoolScriptControlMsg, DevtoolsControlMsg,
@@ -29,7 +30,6 @@ use devtools_traits::{
 use embedder_traits::{EmbedderMsg, EmbedderProxy, PromptDefinition, PromptOrigin, PromptResult};
 use ipc_channel::ipc::{self, IpcSender};
 use log::{debug, warn};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use serde::Serialize;
 use servo_rand::RngCore;