Implement NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE.

third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp b/third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp
index b95120597c5e8e93838348787c43b88cfcd63a15..97543f88f00f73bb9fb40b1134deed255a9e17cf 100644
--- a/third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLIFrameElement.cpp
@@ -39,6 +39,7 @@ using namespace HTMLNames;
 inline HTMLIFrameElement::HTMLIFrameElement(Document& document)
     : HTMLFrameElementBase(iframeTag, document),
       m_didLoadNonEmptyDocument(false),
+      m_collapsedByClient(false),
       m_sandbox(HTMLIFrameElementSandbox::create(this)),
       m_allow(HTMLIFrameElementAllow::create(this)),
       m_referrerPolicy(ReferrerPolicyDefault) {}
@@ -55,6 +56,17 @@ DEFINE_TRACE(HTMLIFrameElement) {
 
 HTMLIFrameElement::~HTMLIFrameElement() {}
 
+void HTMLIFrameElement::setCollapsedByClient(bool collapse) {
+  if (m_collapsedByClient == collapse)
+    return;
+
+  m_collapsedByClient = collapse;
+  if (document().inStyleRecalc())
+    reattachLayoutTree();
+  else
+    lazyReattachIfAttached();
+}
+
 DOMTokenList* HTMLIFrameElement::sandbox() const {
   return m_sandbox.get();
 }
@@ -175,7 +187,8 @@ void HTMLIFrameElement::parseAttribute(
 }
 
 bool HTMLIFrameElement::layoutObjectIsNeeded(const ComputedStyle& style) {
-  return contentFrame() && HTMLElement::layoutObjectIsNeeded(style);
+  return contentFrame() && !m_collapsedByClient &&
+         HTMLFrameElementBase::layoutObjectIsNeeded(style);
 }
 
 LayoutObject* HTMLIFrameElement::createLayoutObject(const ComputedStyle&) {