Modify some gc related layout tests to work with Ignition.

third_party/WebKit/LayoutTests/netinfo/gc-frame-listeners.html

Index: third_party/WebKit/LayoutTests/netinfo/gc-frame-listeners.html
diff --git a/third_party/WebKit/LayoutTests/netinfo/gc-frame-listeners.html b/third_party/WebKit/LayoutTests/netinfo/gc-frame-listeners.html
index 1112ed393c207bd74941034a63baff0fe5440d1c..de80777c564a32191764a24591b7a9ebcb36a9fc 100644
--- a/third_party/WebKit/LayoutTests/netinfo/gc-frame-listeners.html
+++ b/third_party/WebKit/LayoutTests/netinfo/gc-frame-listeners.html
@@ -11,33 +11,27 @@ description('Tests that listeners in closed frames are collected.');
 shouldBe('typeof window.internals.observeGC', '"function"',
 'this test requires window.internals');
 
-var childFrame = document.createElement('iframe');
-// Do not pass the object directly to observeGC function. This may
-// remain live on this function's stack preventing GC from collecting
-// it. Accessing the object inside an inner function will prevent any
-// unneeded references on this function's stack.
-var childFrameObserver = internals.observeGC((() => {return childFrame;})());
-
-document.body.appendChild(childFrame);
-
-var childConnection = childFrame.contentWindow.navigator.connection;
-// Do not pass the object directly to observeGC function. This may
-// remain live on this function's stack preventing GC from collecting
-// it. Accessing the object inside an inner function will prevent any
-// unneeded references on this function's stack.
-var childConnectionObserver = internals.observeGC((() => {return childConnection;})());
+var childFrame, childConnection;
+var childFrameObserver, childConnectionObserver;
 
 var callback = function(e) {
 	testFailed("Should not get here.");
 };
-// Do not pass the object directly to observeGC function. This may
-// remain live on this function's stack preventing GC from collecting
-// it. Accessing the object inside an inner function will prevent any
-// unneeded references on this function's stack.
-var callbackObserver = internals.observeGC((() => {return callback;})());
-
-// Add the event listener and make sure it doesn't get collected.
-childConnection.addEventListener('typechange', callback);
+
+// Do initialization work in an inner function to avoid references to
+// objects remaining live on this function's stack frame.
+// (http://crbug.com/595672/).
+function initialize() {
+    childFrame = document.createElement('iframe');
+    childFrameObserver = internals.observeGC(childFrame);
+    document.body.appendChild(childFrame);
+    childConnection = childFrame.contentWindow.navigator.connection;
+    childConnectionObserver = internals.observeGC(childConnection);
+    callbackObserver = internals.observeGC(callback);
+    childConnection.addEventListener('typechange', callback);
+}
+
+initialize();
 childConnection = null;
 callback = null;

[rmcilroy, 2016/05/20 14:53:39]

nit - could you move childConnection and callback into the initialization
function and avoid (it could just be a function literal passed straight to
addEventListener) and avoid having global variables for them which you need to
null.

[mythria, 2016/05/23 10:35:44]

Done.

 gc();
@@ -46,7 +40,9 @@ shouldBeFalse('childFrameObserver.wasCollected');
 shouldBeFalse('childConnectionObserver.wasCollected');
 shouldBeFalse('callbackObserver.wasCollected');
 
-document.body.removeChild(childFrame);
+// Access objects in an inner function to avoid references to objects
+// remaining live on this function's stack frame (http://crbug.com/595672/).
+(() => {document.body.removeChild(childFrame);})();
 childFrame = null;
 gc();
 shouldBeTrue('childFrameObserver.wasCollected');