Bug 1585217 - Make the layout debugger with -autoclose handle content process crashes. r=heycam

This means that you can use it as a very light-weight crashtest harness by
using:

MOZ_GDB_SLEEP=0 ./mach run -layoutdebug <file> -autoclose

Right now we just never exit otherwise.

Differential Revision: https://phabricator.services.mozilla.com/D47715

--HG--
extra : moz-landing-system : lando

layout/tools/layout-debug/ui/content/layoutdebug.js

@@ -141,6 +141,51 @@ for (let name of COMMANDS) {
   };
 }
 
+const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+
+function autoCloseIfNeeded(aCrash) {
+  if (!gArgs.autoclose) {
+    return;
+  }
+  setTimeout(function() {
+    if (aCrash) {
+      let browser = document.createElementNS(XUL_NS, "browser");
+      // FIXME(emilio): we could use gBrowser if we bothered get the process switches right.
+      //
+      // Doesn't seem worth for this particular case.
+      document.documentElement.appendChild(browser);
+      browser.loadURI("about:crashparent", {
+        triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
+      });
+      return;
+    }
+    if (gArgs.profile && Services.profiler) {
+      dumpProfile();
+    } else {
+      Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit);
+    }
+  }, gArgs.delay * 1000);
+}
+
+const TabCrashedObserver = {
+  observe(subject, topic, data) {
+    switch (topic) {
+      case "ipc:content-shutdown":
+        subject.QueryInterface(Ci.nsIPropertyBag2);
+        if (!subject.get("abnormal")) {
+          return;
+        }
+        break;
+      case "oop-frameloader-crashed":
+        break;
+    }
+    autoCloseIfNeeded(true);
+  }
+};
+
+Services.obs.addObserver(TabCrashedObserver, "ipc:content-shutdown");
+Services.obs.addObserver(TabCrashedObserver, "oop-frameloader-crashed");
+
 function nsLDBBrowserContentListener() {
   this.init();
 }
@@ -174,19 +219,14 @@ nsLDBBrowserContentListener.prototype = {
       this.setButtonEnabled(this.mStopButton, false);
       this.mStatusText.value = gURLBar.value + " loaded";
       this.mLoading = false;
-      if (gArgs.autoclose && gBrowser.currentURI.spec != "about:blank") {
+
+      if (gBrowser.currentURI.spec != "about:blank") {
         // We check for about:blank just to avoid one or two STATE_STOP
         // notifications that occur before the loadURI() call completes.
         // This does mean that --autoclose doesn't work when the URL on
         // the command line is about:blank (or not specified), but that's
         // not a big deal.
-        setTimeout(function() {
-          if (gArgs.profile && Services.profiler) {
-            dumpProfile();
-          } else {
-            Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit);
-          }
-        }, gArgs.delay * 1000);
+        autoCloseIfNeeded(false);
       }
     }
   },