Fix some leaks and failures under valgrind in JS extensions unit tests.

extensions/renderer/resources/serial_service.js

Index: extensions/renderer/resources/serial_service.js
diff --git a/extensions/renderer/resources/serial_service.js b/extensions/renderer/resources/serial_service.js
index 00d137b1ea1cac14226803db8fd829650b2c83c7..83eea23b1a3b4bf5a672360a50d15227e2826a03 100644
--- a/extensions/renderer/resources/serial_service.js
+++ b/extensions/renderer/resources/serial_service.js
@@ -17,8 +17,13 @@ define('serial_service', [
    * Mojo types.
    */
 
-  var service = new serialMojom.SerialServiceProxy(new routerModule.Router(
-      serviceProvider.connectToService(serialMojom.SerialServiceProxy.NAME_)));
+  var unloadEvent = require('unload_event');
+  var serviceRouter = new routerModule.Router(
+      serviceProvider.connectToService(serialMojom.SerialServiceProxy.NAME_));
+  var service = new serialMojom.SerialServiceProxy(serviceRouter);
+  unloadEvent.addListener(function() {
+    serviceRouter.close();
+  });

[not at google - send to devlin, 2014/08/27 19:28:58]

Hm, why does the destruction of |serviceRouter| (via the context being
destroyed) not cause it to automatically close? All of its references should
have gone. I.e. is it not enough to just call the RunGCForTesting method and not
change any code in here?

[Sam McNally, 2014/08/28 07:06:51]

It appears "kFullGarbageCollection" doesn't mean what I thought it meant. The
old version does work as expected if the GC is run enough.

 
   function getDevices() {
     return service.getDevices().then(function(response) {