Auto merge of #20132 - nakul02:issue_19223, r=jdm

Profiler for blocked IpcReceiver::recv()

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Implements feature #19223

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #19223 (github issue number if applicable).

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- [x] There are tests for these changes

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WIP.
@jdm - this is the new profiler : "Blocked at IPC Receive"
Should I dig through all the calls to `ipc::channel` and replace them with this profiled `IpcReceiver`?

![screenshot from 2018-02-27 01-35-37](https://user-images.githubusercontent.com/5394361/36721061-b46edea4-1b5e-11e8-91d6-7faba742f237.png)

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tests/unit/profile/Cargo.toml

@@ -16,3 +16,5 @@ profile_traits = {path = "../../../components/profile_traits"}
 
 # Work around https://github.com/alexcrichton/jemallocator/issues/19
 servo_allocator = {path = "../../../components/allocator"}
+servo_config = {path = "../../../components/config"}
+

tests/unit/profile/lib.rs

@@ -8,5 +8,6 @@ extern crate ipc_channel;
 extern crate profile;
 extern crate profile_traits;
 extern crate servo_allocator;
+extern crate servo_config;
 
 mod time;

tests/unit/profile/time.rs

@@ -4,7 +4,11 @@
 
 use ipc_channel::ipc;
 use profile::time;
-use profile_traits::time::ProfilerMsg;
+use profile_traits::ipc as ProfiledIpc;
+use profile_traits::time::{ProfilerCategory, ProfilerData, ProfilerMsg};
+use servo_config::opts::OutputOptions;
+use std::thread;
+use std::time::Duration;
 
 #[test]
 fn time_profiler_smoke_test() {
@@ -37,6 +41,29 @@ fn time_profiler_stats_test() {
     assert_eq!(13.2599, odd_max);
 }
 
+#[test]
+fn channel_profiler_test() {
+    let chan = time::Profiler::create(&Some(OutputOptions::Stdout(5.0)), None);
+    let (profiled_sender, profiled_receiver) = ProfiledIpc::channel(chan.clone()).unwrap();
+    thread::spawn(move || {
+        thread::sleep(Duration::from_secs(2));
+        profiled_sender.send(43).unwrap();
+    });
+
+    let val_profile_receiver = profiled_receiver.recv().unwrap();
+    assert_eq!(val_profile_receiver, 43);
+
+    let (sender, receiver) = ipc::channel().unwrap();
+    chan.send(ProfilerMsg::Get((ProfilerCategory::IpcReceiver, None), sender.clone()));
+
+    match receiver.recv().unwrap() {
+        // asserts that the time spent in the sleeping thread is more than 1500 milliseconds
+        ProfilerData::Record(time_data) => assert!(time_data[0] > 1.5e3),
+        ProfilerData::NoRecords => assert!(false),
+    };
+
+}
+
 #[cfg(debug_assertions)]
 #[test]
 #[should_panic]