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 3d8de52059e3a13e54c599edfd384fcbefb73f52..f5165d748096cae185c122d9e71cfd991e24867c 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),
       did_load_non_empty_document_(false),
+      collapsed_by_client_(false),
       sandbox_(HTMLIFrameElementSandbox::Create(this)),
       allow_(HTMLIFrameElementAllow::Create(this)),
       referrer_policy_(kReferrerPolicyDefault) {}
@@ -54,6 +55,17 @@ DEFINE_TRACE(HTMLIFrameElement) {
 
 HTMLIFrameElement::~HTMLIFrameElement() {}
 
+void HTMLIFrameElement::SetCollapsedByClient(bool collapse) {
+  if (collapsed_by_client_ == collapse)
+    return;
+
+  collapsed_by_client_ = collapse;
+  if (GetDocument().InStyleRecalc())

[dcheng, 2017/04/18 07:01:36]

Can you help me understand why this would be called in the middle of style
recalc? And in that case, why do we need to do something different?

[engedy, 2017/04/20 11:45:43]

I was just trying to be defensive here. While I have found no obvious pumping of
message loops during style recalc, I wasn't 100% sure there is no "sneaky"
pumping of message loops. :-)

If you can confirm that that is indeed the intention, then this indeed can be
simplified.

+    ReattachLayoutTree();
+  else
+    LazyReattachIfAttached();
+}
+
 DOMTokenList* HTMLIFrameElement::sandbox() const {
   return sandbox_.Get();
 }
@@ -165,7 +177,8 @@ void HTMLIFrameElement::ParseAttribute(
 }
 
 bool HTMLIFrameElement::LayoutObjectIsNeeded(const ComputedStyle& style) {
-  return ContentFrame() && HTMLElement::LayoutObjectIsNeeded(style);
+  return ContentFrame() && !collapsed_by_client_ &&
+         HTMLElement::LayoutObjectIsNeeded(style);
 }
 
 LayoutObject* HTMLIFrameElement::CreateLayoutObject(const ComputedStyle&) {