Bug 1960602 - More explicitly block bfcache when a subframe is loading. r=smaug

The test now passes with http2/http3 (where it didn't use to because the
frame was not OOP in that case).

Differential Revision: https://phabricator.services.mozilla.com/D245741

docshell/base/CanonicalBrowsingContext.cpp

@@ -2987,6 +2987,9 @@ static void LogBFCacheBlockingForDoc(BrowsingContext* aBrowsingContext,
   if (aBFCacheCombo & BFCacheStatus::ACTIVE_LOCK) {
     MOZ_LOG(gSHIPBFCacheLog, LogLevel::Debug, (" * has active Web Locks"));
   }
+  if (aBFCacheCombo & BFCacheStatus::PAGE_LOADING) {
+    MOZ_LOG(gSHIPBFCacheLog, LogLevel::Debug, (" * has page loading"));
+  }
 }
 
 bool CanonicalBrowsingContext::AllowedInBFCache(

docshell/test/navigation/mochitest.toml

@@ -105,10 +105,6 @@ support-files = [
   "iframe_slow_onload.html",
   "iframe_slow_onload_inner.html",
 ]
-skip-if = [
-  "http3",
-  "http2",
-]
 
 ["test_bug13871.html"]
 skip-if = [

docshell/test/navigation/test_blockBFCache.html

@@ -98,7 +98,7 @@ const blockBFCacheTests = [
   },
 ];
 
-if (SpecialPowers.effectiveIsolationStrategy() == SpecialPowers.ISOLATION_STRATEGY.IsolateEverything) {
+if (SpecialPowers.Services.appinfo.sessionHistoryInParent) {
   blockBFCacheTests.push({
     name: "Loading OOP iframe",
     test: () => {

dom/base/Document.cpp

@@ -8217,6 +8217,13 @@ void Document::SetScriptGlobalObject(
   nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(mScriptGlobalObject);
   mWindow = window;
 
+  if (mReadyState != READYSTATE_COMPLETE) {
+    if (auto* wgc = GetWindowGlobalChild()) {
+      // This gets unset on OnPageShow.
+      wgc->BlockBFCacheFor(BFCacheStatus::PAGE_LOADING);
+    }
+  }
+
   // Now that we know what our window is, we can flush the CSP errors to the
   // Web Console. We are flushing all messages that occurred and were stored in
   // the queue prior to this point.
@@ -12353,6 +12360,10 @@ void Document::OnPageShow(bool aPersisted, EventTarget* aDispatchStartTarget,
     DispatchPageTransition(target, u"pageshow"_ns, inFrameLoaderSwap,
                            aPersisted, aOnlySystemGroup);
   }
+
+  if (auto* wgc = GetWindowGlobalChild()) {
+    wgc->UnblockBFCacheFor(BFCacheStatus::PAGE_LOADING);
+  }
 }
 
 static void DispatchFullscreenChange(Document& aDocument, nsINode* aTarget) {

dom/base/Document.h

@@ -325,6 +325,7 @@ enum BFCacheStatus {
   BEFOREUNLOAD_LISTENER = 1 << 15,       // Status 15
   ACTIVE_LOCK = 1 << 16,                 // Status 16
   ACTIVE_WEBTRANSPORT = 1 << 17,         // Status 17
+  PAGE_LOADING = 1 << 18,                // Status 18
 };
 
 }  // namespace dom

dom/ipc/WindowGlobalParent.cpp

@@ -1279,6 +1279,7 @@ nsCString BFCacheStatusToString(uint32_t aFlags) {
   ADD_BFCACHESTATUS_TO_STRING(NOT_ONLY_TOPLEVEL_IN_BCG);
   ADD_BFCACHESTATUS_TO_STRING(BEFOREUNLOAD_LISTENER);
   ADD_BFCACHESTATUS_TO_STRING(ACTIVE_LOCK);
+  ADD_BFCACHESTATUS_TO_STRING(PAGE_LOADING);
 
 #undef ADD_BFCACHESTATUS_TO_STRING