Implement basic Time To First Paint and First Contentful Paint PWMs

components/script_layout_interface/Cargo.toml

@@ -22,6 +22,7 @@ html5ever = "0.18"
 ipc-channel = "0.8"
 libc = "0.2"
 log = "0.3.5"
+metrics = {path = "../metrics"}
 msg = {path = "../msg"}
 net_traits = {path = "../net_traits"}
 profile_traits = {path = "../profile_traits"}

components/script_layout_interface/lib.rs

@@ -24,6 +24,7 @@ extern crate ipc_channel;
 extern crate libc;
 #[macro_use]
 extern crate log;
+extern crate metrics;
 extern crate msg;
 extern crate net_traits;
 extern crate profile_traits;

components/script_layout_interface/message.rs

@@ -7,6 +7,7 @@ use app_units::Au;
 use euclid::{Point2D, Rect};
 use gfx_traits::Epoch;
 use ipc_channel::ipc::{IpcReceiver, IpcSender};
+use metrics::PaintTimeMetrics;
 use msg::constellation_msg::PipelineId;
 use net_traits::image_cache::ImageCache;
 use profile_traits::mem::ReportsChan;
@@ -89,6 +90,9 @@ pub enum Msg {
 
     /// Tells layout that script has added some paint worklet modules.
     RegisterPaint(Atom, Vec<Atom>, Arc<Painter>),
+
+    /// Send to layout the precise time when the navigation started.
+    SetNavigationStart(f64),
 }
 
 
@@ -158,4 +162,5 @@ pub struct NewLayoutThreadInfo {
     pub image_cache: Arc<ImageCache>,
     pub content_process_shutdown_chan: Option<IpcSender<()>>,
     pub layout_threads: usize,
+    pub paint_time_metrics: PaintTimeMetrics,
 }