Add an about:memory page (#35728)

This patch exposes a servo internal DOM API that is only made available to about:
pages on the navigator object to request memory reports. The about:memory page itself is
loaded like other html resources (eg. bad cert, net error) and makes use of this new API.

On the implementation side, notable changes:
- components/script/routed_promise.rs abstracts the setup used to fulfill a promise when the
  work needs to be routed through the constellation. The goal is to migrate other similar
  promise APIs in followup (eg. dom/webgpu/gpu.rs, bluetooth.rs).
- a new message is added to request a report from the memory reporter, and the memory reporter
  creates a json representation of the set of memory reports.
- the post-processing of memory reports is done in Javascript in the about-memory.html page,
  providing the same results as the current Rust code that outputs to stdout. We can decide
  later if we want to remove the current output.

Signed-off-by: webbeef <me@webbeef.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/components/shared/profile/mem.rs b/components/shared/profile/mem.rs
index 5b92d2eee17..f2d67dec43b 100644
--- a/components/shared/profile/mem.rs
+++ b/components/shared/profile/mem.rs
@@ -190,6 +190,13 @@ macro_rules! path {
     }}
 }
 
+/// The results produced by the memory reporter.
+#[derive(Debug, Deserialize, Serialize)]
+pub struct MemoryReportResult {
+    /// The stringified output.
+    pub content: String,
+}
+
 /// Messages that can be sent to the memory profiler thread.
 #[derive(Debug, Deserialize, Serialize)]
 pub enum ProfilerMsg {
@@ -208,4 +215,7 @@ pub enum ProfilerMsg {
 
     /// Tells the memory profiler to shut down.
     Exit,
+
+    /// Triggers sending back the memory profiling metrics,
+    Report(IpcSender<MemoryReportResult>),
 }