Auto merge of #19498 - ferjm:pwm.f64, r=jdm

Fix float conversion of paint timing metrics

This is a follow up of #19077

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors

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1 files changed, 11 insertions, 2 deletions

diff --git a/components/metrics/lib.rs b/components/metrics/lib.rs
index bd2d488f100..72706d0a0a7 100644
--- a/components/metrics/lib.rs
+++ b/components/metrics/lib.rs
@@ -46,6 +46,15 @@ pub const MAX_TASK_NS: u64 = 50000000;
 /// 10 second window (in ns)
 const INTERACTIVE_WINDOW_SECONDS_IN_NS: u64 = 10000000000;
 
+pub trait ToMs<T> {
+    fn to_ms(&self) -> T;
+}
+
+impl ToMs<f64> for u64 {
+    fn to_ms(&self) -> f64 {
+        *self as f64 / 1000000.
+    }
+}
 
 fn set_metric<U: ProgressiveWebMetric>(
     pwm: &U,
@@ -85,8 +94,8 @@ fn set_metric<U: ProgressiveWebMetric>(
 
     // Print the metric to console if the print-pwm option was given.
     if opts::get().print_pwm {
-        println!("Navigation start: {}", pwm.get_navigation_start().unwrap());
-        println!("{:?} {:?}", metric_type, time);
+        println!("Navigation start: {}", pwm.get_navigation_start().unwrap().to_ms());
+        println!("{:?} {:?}", metric_type, time.to_ms());
     }
 
 }