Backed out changeset f768135b85f2 (bug 1746524) for causing perf regressions

docshell/base/CanonicalBrowsingContext.cpp

@@ -2188,18 +2188,6 @@ bool CanonicalBrowsingContext::HasCreatedMediaController() const {
 
 bool CanonicalBrowsingContext::SupportsLoadingInParent(
     nsDocShellLoadState* aLoadState, uint64_t* aOuterWindowId) {
-  // We only support parent controlled navigation with Fission.
-  if (!StaticPrefs::browser_tabs_documentchannel_parent_controlled() ||
-      !mozilla::FissionAutostart()) {
-    return false;
-  }
-
-  // We currently only support starting loads directly from the
-  // CanonicalBrowsingContext for top-level BCs.
-  if (!IsTopContent() || !GetContentParent()) {
-    return false;
-  }
-
   // We currently don't support initiating loads in the parent when they are
   // watched by devtools. This is because devtools tracks loads using content
   // process notifications, which happens after the load is initiated in this
@@ -2250,6 +2238,15 @@ bool CanonicalBrowsingContext::SupportsLoadingInParent(
 
 bool CanonicalBrowsingContext::LoadInParent(nsDocShellLoadState* aLoadState,
                                             bool aSetNavigating) {
+  // We currently only support starting loads directly from the
+  // CanonicalBrowsingContext for top-level BCs.
+  // We currently only support starting loads directly from the
+  // CanonicalBrowsingContext for top-level BCs.
+  if (!IsTopContent() || !GetContentParent() ||
+      !StaticPrefs::browser_tabs_documentchannel_parent_controlled()) {
+    return false;
+  }
+
   uint64_t outerWindowId = 0;
   if (!SupportsLoadingInParent(aLoadState, &outerWindowId)) {
     return false;
@@ -2269,9 +2266,17 @@ bool CanonicalBrowsingContext::LoadInParent(nsDocShellLoadState* aLoadState,
 
 bool CanonicalBrowsingContext::AttemptSpeculativeLoadInParent(
     nsDocShellLoadState* aLoadState) {
+  // We currently only support starting loads directly from the
+  // CanonicalBrowsingContext for top-level BCs.
+  // We currently only support starting loads directly from the
+  // CanonicalBrowsingContext for top-level BCs.
+  if (!IsTopContent() || !GetContentParent() ||
+      (StaticPrefs::browser_tabs_documentchannel_parent_controlled())) {
+    return false;
+  }
+
   uint64_t outerWindowId = 0;
-  if (!StaticPrefs::browser_tabs_documentchannel_speculative_load() ||
-      !SupportsLoadingInParent(aLoadState, &outerWindowId)) {
+  if (!SupportsLoadingInParent(aLoadState, &outerWindowId)) {
     return false;
   }
 

modules/libpref/init/StaticPrefList.yaml

@@ -1620,13 +1620,6 @@
 # If set, use DocumentChannel to directly initiate loads entirely
 # from parent-process BrowsingContexts
 - name: browser.tabs.documentchannel.parent-controlled
-  type: bool
-  value: true
-  mirror: always
-
-# If set, use DocumentChannel to attempt a speculative load from the
-# parent whenever it's not possible to directly load from the parent.
-- name: browser.tabs.documentchannel.speculative-load
   type: bool
   value: false
   mirror: always