Don't create layout objects for children of display-none iframes.

third_party/WebKit/Source/web/tests/WebFrameTest.cpp

Index: third_party/WebKit/Source/web/tests/WebFrameTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/WebFrameTest.cpp b/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
index 6841b213fbd6e180f7a97976cf27cd7a8527820a..e23c83bfba2820cba71c627560499f8b515c9a8b 100644
--- a/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
+++ b/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
@@ -10781,6 +10781,76 @@ TEST_F(WebFrameTest, UniqueNames) {
   EXPECT_EQ(10u, names.size());
 }
 
+namespace {
+bool DocumentElementChildrenHaveLayoutObjects(Document* doc) {
+  for (Node* child = doc->documentElement()->firstChild(); child;

[esprehn, 2016/12/15 21:36:48]

There's no need to check this, if the documentElement has no layoutObject, then
it's children can't have them either.

!documentElement()->layoutObject() is enough.

[erikchen, 2016/12/16 20:56:12]

but the document element does have a layout object. We overrode
LayoutView::canHaveChildren() so that it can't have children.

+       child = child->nextSibling()) {
+    if (child->layoutObject())
+      return true;
+  }
+  return false;
+}
+}  // namespace
+
+TEST_F(WebFrameTest, DisplayNoneIFrameHasNoLayoutObjects) {

[esprehn, 2016/12/15 21:36:48]

If you use a SimTest instead this whole this can be much simpler and you don't
need any of the external files.

[erikchen, 2016/12/16 20:56:12]

Done.

+  registerMockedHttpURLLoad("single_invisible_iframe.html");
+  registerMockedHttpURLLoad("visible_iframe.html");
+  FrameTestHelpers::WebViewHelper webViewHelper;
+  webViewHelper.initializeAndLoad(m_baseURL + "single_invisible_iframe.html",
+                                  true);
+
+  WebLocalFrameImpl* frame = webViewHelper.webView()->mainFrameImpl();
+  Element* element = frame->frame()->document()->querySelector("iframe");
+  HTMLFrameOwnerElement* frameOwnerElement =
+      static_cast<HTMLFrameOwnerElement*>(element);
+
+  Document* iframeDoc = frameOwnerElement->contentDocument();
+  EXPECT_FALSE(DocumentElementChildrenHaveLayoutObjects(iframeDoc));
+
+  // Changing the display from 'none' -> 'block' should cause layout objects to
+  // appear.
+  frame->executeScript(
+      WebScriptSource("d = document.querySelector('iframe');"
+                      "d.style.display = 'block';"));
+  frame->view()->updateAllLifecyclePhases();
+  runPendingTasks();
+  EXPECT_TRUE(DocumentElementChildrenHaveLayoutObjects(iframeDoc));
+
+  // Changing the display from 'block' -> 'none' should cause layout objects to
+  // disappear.
+  frame->executeScript(

[esprehn, 2016/12/15 21:36:48]

No need for JS, you can just do
element->setInlineStyleProperty(CSSPropertyDisplay, CSSValueNone);

[erikchen, 2016/12/16 20:56:12]

Done.

+      WebScriptSource("d = document.querySelector('iframe');"
+                      "d.style.display = 'none';"));
+
+  frame->view()->updateAllLifecyclePhases();
+  runPendingTasks();
+  EXPECT_FALSE(DocumentElementChildrenHaveLayoutObjects(iframeDoc));
+}
+
+TEST_F(WebFrameTest, NormalIFrameHasLayoutObjects) {

[esprehn, 2016/12/15 21:36:48]

SimTests will make this simpler:
ex.
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/web/tests/Docu...

[erikchen, 2016/12/16 20:56:12]

Done.

+  registerMockedHttpURLLoad("single_iframe.html");
+  registerMockedHttpURLLoad("visible_iframe.html");
+  FrameTestHelpers::WebViewHelper webViewHelper;
+  webViewHelper.initializeAndLoad(m_baseURL + "single_iframe.html", true);
+
+  WebLocalFrameImpl* frame = webViewHelper.webView()->mainFrameImpl();
+  Element* element = frame->frame()->document()->querySelector("iframe");
+  HTMLFrameOwnerElement* frameOwnerElement =
+      static_cast<HTMLFrameOwnerElement*>(element);
+
+  Document* iframeDoc = frameOwnerElement->contentDocument();
+  EXPECT_TRUE(DocumentElementChildrenHaveLayoutObjects(iframeDoc));
+
+  // Changing the display from 'block' -> 'none' should cause layout objects to
+  // disappear.
+  frame->executeScript(
+      WebScriptSource("d = document.querySelector('iframe');"
+                      "d.style.display = 'none';"));
+  frame->view()->updateAllLifecyclePhases();
+  runPendingTasks();
+  EXPECT_FALSE(DocumentElementChildrenHaveLayoutObjects(iframeDoc));
+}
+
 TEST_F(WebFrameTest, NoLoadingCompletionCallbacksInDetach) {
   class LoadingObserverFrameClient
       : public FrameTestHelpers::TestWebFrameClient {