Bug 1073352, part 1 - Make the DOMWINDOW and DOCSHELL leak detector work with e10s. r=jmaher

This reworks how the Mochitest DOMWINDOW and DOCSHELL leak detector works. Rather than
collecting immediately in the top-level script, it sends a message to all processes
telling them to carry out collections. Each process prints out a message when it has
finished the collections. This message is used by the test harness to decide when windows
and docshells for that process should be have been destroyed.

build/automationutils.py

@@ -445,7 +445,7 @@ class ShutdownLeaks(object):
     self.leakedWindows = {}
     self.leakedDocShells = set()
     self.currentTest = None
-    self.seenShutdown = False
+    self.seenShutdown = set()
 
   def log(self, message):
     if message['action'] == 'log':
@@ -454,8 +454,9 @@ class ShutdownLeaks(object):
           self._logWindow(line)
         elif line[2:10] == "DOCSHELL":
           self._logDocShell(line)
-        elif line.startswith("TEST-START | Shutdown"):
-          self.seenShutdown = True
+        elif line.startswith("Completed ShutdownLeaks collections in process"):
+          pid = int(line.split()[-1])
+          self.seenShutdown.add(pid)
     elif message['action'] == 'test_start':
       fileName = message['test'].replace("chrome://mochitests/content/browser/", "")
       self.currentTest = {"fileName": fileName, "windows": set(), "docShells": set()}
@@ -499,7 +500,7 @@ class ShutdownLeaks(object):
         windows.add(key)
       else:
         windows.discard(key)
-    elif self.seenShutdown and not created:
+    elif int(pid) in self.seenShutdown and not created:
       self.leakedWindows[key] = self._parseValue(line, "url")
 
   def _logDocShell(self, line):
@@ -520,7 +521,7 @@ class ShutdownLeaks(object):
         docShells.add(key)
       else:
         docShells.discard(key)
-    elif self.seenShutdown and not created:
+    elif int(pid) in self.seenShutdown and not created:
       self.leakedDocShells.add(key)
 
   def _parseValue(self, line, name):

testing/mochitest/ShutdownLeaksCollector.jsm

@@ -0,0 +1,48 @@
+/* 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/. */
+
+var Ci = Components.interfaces;
+var Cc = Components.classes;
+var Cu = Components.utils;
+
+Cu.import("resource://gre/modules/Services.jsm");
+
+this.EXPORTED_SYMBOLS = ["ContentCollector"];
+
+// This listens for the message "browser-test:collect-request". When it gets it,
+// it runs some GCs and CCs, then prints out a message indicating the collections
+// are complete. Mochitest uses this information to determine when windows and
+// docshells should be destroyed.
+
+var ContentCollector = {
+  init: function() {
+    let cpmm = Cc["@mozilla.org/childprocessmessagemanager;1"]
+                 .getService(Ci.nsISyncMessageSender);
+    cpmm.addMessageListener("browser-test:collect-request", this);
+  },
+
+  receiveMessage: function(aMessage) {
+    switch (aMessage.name) {
+      case "browser-test:collect-request":
+        Services.obs.notifyObservers(null, "memory-pressure", "heap-minimize");
+
+        Cu.forceGC();
+        Cu.forceCC();
+
+        Cu.schedulePreciseShrinkingGC(() => {
+          Cu.forceCC();
+
+          let pid = Cc["@mozilla.org/xre/app-info;1"].getService(Ci.nsIXULRuntime).processID;
+          dump("Completed ShutdownLeaks collections in process " + pid + "\n")});
+
+          let cpmm = Cc["@mozilla.org/childprocessmessagemanager;1"]
+                       .getService(Ci.nsISyncMessageSender);
+          cpmm.removeMessageListener("browser-test:collect-request", this);
+
+        break;
+    }
+  }
+
+};
+ContentCollector.init();

testing/mochitest/browser-test.js

@@ -86,6 +86,9 @@ function testInit() {
   if (gConfig.e10s) {
     e10s_init();
   }
+  let globalMM = Cc["@mozilla.org/globalmessagemanager;1"]
+                     .getService(Ci.nsIMessageListenerManager);
+  globalMM.loadFrameScript("chrome://mochikit/content/shutdown-leaks-collector.js", true);
 }
 
 function Tester(aTests, aDumper, aCallback) {
@@ -571,6 +574,10 @@ Tester.prototype = {
           // and thus get rid of more false leaks like already terminated workers.
           Services.obs.notifyObservers(null, "memory-pressure", "heap-minimize");
 
+          let ppmm = Cc["@mozilla.org/parentprocessmessagemanager;1"]
+                       .getService(Ci.nsIMessageBroadcaster);
+          ppmm.broadcastAsyncMessage("browser-test:collect-request");
+
           checkForLeakedGlobalWindows(aResults => {
             if (aResults.length == 0) {
               this.finish();

testing/mochitest/jar.mn

@@ -10,6 +10,8 @@ mochikit.jar:
   content/cc-analyzer.js (cc-analyzer.js)
   content/chrome-harness.js (chrome-harness.js)
   content/mochitest-e10s-utils.js (mochitest-e10s-utils.js)
+  content/shutdown-leaks-collector.js (shutdown-leaks-collector.js)
+  content/ShutdownLeaksCollector.jsm (ShutdownLeaksCollector.jsm)
   content/harness.xul (harness.xul)
   content/redirect.html (redirect.html)
   content/server.js (server.js)

testing/mochitest/shutdown-leaks-collector.js

@@ -0,0 +1,7 @@
+/* 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/. */
+
+// We run this code in a .jsm rather than here to avoid keeping the current
+// compartment alive.
+Components.utils.import("chrome://mochikit/content/ShutdownLeaksCollector.jsm");