Bug 1721217 - Part 1: Enable parent controlled loads via DC, r=nika

Differential Revision: https://phabricator.services.mozilla.com/D126841

docshell/base/CanonicalBrowsingContext.cpp

@@ -2031,7 +2031,8 @@ bool CanonicalBrowsingContext::LoadInParent(nsDocShellLoadState* aLoadState,
   // We currently only support starting loads directly from the
   // CanonicalBrowsingContext for top-level BCs.
   if (!IsTopContent() || !GetContentParent() ||
-      !StaticPrefs::browser_tabs_documentchannel_parent_controlled()) {
+      !StaticPrefs::browser_tabs_documentchannel_parent_controlled() ||
+      !mozilla::SessionHistoryInParent()) {
     return false;
   }
 
@@ -2040,6 +2041,8 @@ bool CanonicalBrowsingContext::LoadInParent(nsDocShellLoadState* aLoadState,
     return false;
   }
 
+  MOZ_ASSERT(!net::SchemeIsJavascript(aLoadState->URI()));
+
   // Note: If successful, this will recurse into StartDocumentLoad and
   // set mCurrentLoad to the DocumentLoadListener instance created.
   // Ideally in the future we will only start loads from here, and we can
@@ -2055,7 +2058,8 @@ bool CanonicalBrowsingContext::AttemptSpeculativeLoadInParent(
   // We currently only support starting loads directly from the
   // CanonicalBrowsingContext for top-level BCs.
   if (!IsTopContent() || !GetContentParent() ||
-      StaticPrefs::browser_tabs_documentchannel_parent_controlled()) {
+      (StaticPrefs::browser_tabs_documentchannel_parent_controlled() &&
+       mozilla::SessionHistoryInParent())) {
     return false;
   }
 
@@ -2075,7 +2079,7 @@ bool CanonicalBrowsingContext::StartDocumentLoad(
   // If we're controlling loads from the parent, then starting a new load means
   // that we need to cancel any existing ones.
   if (StaticPrefs::browser_tabs_documentchannel_parent_controlled() &&
-      mCurrentLoad) {
+      mozilla::SessionHistoryInParent() && mCurrentLoad) {
     mCurrentLoad->Cancel(NS_BINDING_ABORTED);
   }
   mCurrentLoad = aLoad;

modules/libpref/init/StaticPrefList.yaml

@@ -1335,7 +1335,7 @@
 # from parent-process BrowsingContexts
 - name: browser.tabs.documentchannel.parent-controlled
   type: bool
-  value: false
+  value: true
   mirror: always
 
 # Testing-only pref which makes data: URIs be loaded in a "web" content process

netwerk/ipc/DocumentLoadListener.cpp

@@ -2234,10 +2234,6 @@ DocumentLoadListener::OnStartRequest(nsIRequest* aRequest) {
 
       DisconnectListeners(NS_BINDING_ABORTED, NS_BINDING_ABORTED, true);
 
-      // XXX(anny) This is currently a dead code path because parent-controlled
-      // DC pref is off. When we enable the pref, we might get extra STATE_START
-      // progress events
-
       // Notify the docshell that it should load using the newly connected
       // channel
       browserParent->ResumeLoad(mLoadIdentifier);