Auto merge of #21941 - codehag:devtools-add-stylesheets-actor, r=jdm

DevTools - add preliminary StyleSheetActor

Based on an error coming from devtools, that the server did not support a stylesheets actor, this patch introduces a [StyleSheetsActor](https://searchfox.org/mozilla-central/rev/26b40a44691e0710838130b614c2f2662bc91eec/devtools/server/actors/stylesheets.js#590-853). It has no methods yet, but it is a small step towards getting the devtools up and running.

Before the change:
No stylesheet editor

After the change we can see that the style editor now loads. It has no information but I will get to that later.
<img width="902" alt="screen shot 2018-10-14 at 12 51 51" src="https://user-images.githubusercontent.com/26968615/46915813-61192900-cfb1-11e8-8382-3d9dc8db4114.png">

Status after this PR:
* Debugger does not load
* Netmonitor does not load
* Console is loading but doesn't receive messages.
* Inspector is, but does not have any information
* style editor is *now loading* but does not have any information
* Performance is an out of date tab, and will likely need to be changed substantially

next steps for this will be to implement the [protocol methods](https://searchfox.org/mozilla-central/source/devtools/shared/specs/stylesheets.js#74-95)

I am not too sure how to test this, it doesn't look like there are tests yet for the devtools, is that right?

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components/devtools/actors/browsing_context.rs

@@ -65,6 +65,7 @@ pub struct BrowsingContextActorMsg {
     timelineActor: String,
     profilerActor: String,
     performanceActor: String,
+    styleSheetsActor: String,
 }
 
 pub struct BrowsingContextActor {
@@ -76,6 +77,7 @@ pub struct BrowsingContextActor {
     pub timeline: String,
     pub profiler: String,
     pub performance: String,
+    pub styleSheets: String,
     pub thread: String,
 }
 
@@ -174,6 +176,7 @@ impl BrowsingContextActor {
             timelineActor: self.timeline.clone(),
             profilerActor: self.profiler.clone(),
             performanceActor: self.performance.clone(),
+            styleSheetsActor: self.styleSheets.clone(),
         }
     }
 }

components/devtools/actors/stylesheets.rs

@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use actor::{Actor, ActorMessageStatus, ActorRegistry};
+use serde_json::{Map, Value};
+use std::net::TcpStream;
+
+pub struct StyleSheetsActor {
+    pub name: String,
+}
+
+impl Actor for StyleSheetsActor {
+    fn name(&self) -> String {
+        self.name.clone()
+    }
+    fn handle_message(
+        &self,
+        _: &ActorRegistry,
+        _: &str,
+        _: &Map<String, Value>,
+        _: &mut TcpStream,
+    ) -> Result<ActorMessageStatus, ()> {
+        Ok(ActorMessageStatus::Ignored)
+    }
+}
+
+impl StyleSheetsActor {
+    pub fn new(name: String) -> StyleSheetsActor {
+        StyleSheetsActor { name: name }
+    }
+}
+

components/devtools/lib.rs

@@ -33,6 +33,7 @@ use actors::network_event::{EventActor, NetworkEventActor, ResponseStartMsg};
 use actors::performance::PerformanceActor;
 use actors::profiler::ProfilerActor;
 use actors::root::RootActor;
+use actors::stylesheets::StyleSheetsActor;
 use actors::thread::ThreadActor;
 use actors::timeline::TimelineActor;
 use actors::worker::WorkerActor;
@@ -65,6 +66,7 @@ mod actors {
     pub mod performance;
     pub mod profiler;
     pub mod root;
+    pub mod stylesheets;
     pub mod thread;
     pub mod timeline;
     pub mod worker;
@@ -216,7 +218,7 @@ fn run_server(
         let (pipeline, worker_id) = ids;
 
         //TODO: move all this actor creation into a constructor method on BrowsingContextActor
-        let (target, console, inspector, timeline, profiler, performance, thread) = {
+        let (target, console, inspector, timeline, profiler, performance, styleSheets, thread) = {
             let console = ConsoleActor {
                 name: actors.new_name("console"),
                 script_chan: script_sender.clone(),
@@ -237,6 +239,9 @@ fn run_server(
             let profiler = ProfilerActor::new(actors.new_name("profiler"));
             let performance = PerformanceActor::new(actors.new_name("performance"));
 
+            // the strange switch between styleSheets and stylesheets is due
+            // to an inconsistency in devtools. See Bug #1498893 in bugzilla
+            let styleSheets = StyleSheetsActor::new(actors.new_name("stylesheets"));
             let thread = ThreadActor::new(actors.new_name("context"));
 
             let DevtoolsPageInfo { title, url } = page_info;
@@ -249,6 +254,7 @@ fn run_server(
                 timeline: timeline.name(),
                 profiler: profiler.name(),
                 performance: performance.name(),
+                styleSheets: styleSheets.name(),
                 thread: thread.name(),
             };
 
@@ -262,6 +268,7 @@ fn run_server(
                 timeline,
                 profiler,
                 performance,
+                styleSheets,
                 thread,
             )
         };
@@ -283,6 +290,7 @@ fn run_server(
         actors.register(Box::new(timeline));
         actors.register(Box::new(profiler));
         actors.register(Box::new(performance));
+        actors.register(Box::new(styleSheets));
         actors.register(Box::new(thread));
     }