Fix exception on timeout in SanityTest.js, and increase the timeout t…

…ime. (bug 1205819, r=mchang)

toolkit/components/gfx/SanityTest.js

@@ -20,7 +20,7 @@ const DEVICE_PREF="sanity-test.device-id";
 const VERSION_PREF="sanity-test.version";
 const DISABLE_VIDEO_PREF="media.hardware-video-decoding.failed";
 const RUNNING_PREF="sanity-test.running";
-const TIMEOUT_SEC=6;
+const TIMEOUT_SEC=20;
 
 // GRAPHICS_SANITY_TEST histogram enumeration values
 const TEST_PASSED=0;
@@ -220,11 +220,14 @@ var listener = {
     this.utils = null;
     this.canvas = null;
 
-    this.messages.forEach((msgName) => {
-      this.mm.removeMessageListener(msgName, this);
-    });
+    if (this.mm) {
+      // We don't have a MessageManager if onWindowLoaded never fired.
+      this.messages.forEach((msgName) => {
+        this.mm.removeMessageListener(msgName, this);
+      });
 
-    this.mm = null;
+      this.mm = null;
+    }
 
     // Remove the annotation after we've cleaned everything up, to catch any
     // incidental crashes from having performed the sanity test.