Bug 1616171 - P2: nsILoadInfo::targetBrowsingContext attribute. r=mattwoodrow,nika

This new attribute on nsILoadInfo allows retrieving the BrowsingContext and
BrowsingContextId for the BC of the document to be loaded by an nsILoadInfo.

Differential Revision: https://phabricator.services.mozilla.com/D63127

--HG--
extra : moz-landing-system : lando

browser/components/sessionstore/SessionStore.jsm

@@ -2624,15 +2624,10 @@ var SessionStoreInternal = {
     }
 
     // Check that the document has a corresponding BrowsingContext.
-    let browsingContext;
-    let isSubframe = false;
-    let cp = channel.loadInfo.externalContentPolicyType;
-    if (cp == Ci.nsIContentPolicy.TYPE_DOCUMENT) {
-      browsingContext = channel.loadInfo.browsingContext;
-    } else {
-      browsingContext = channel.loadInfo.frameBrowsingContext;
-      isSubframe = true;
-    }
+    let browsingContext = channel.loadInfo.targetBrowsingContext;
+    let isSubframe =
+      channel.loadInfo.externalContentPolicyType !=
+      Ci.nsIContentPolicy.TYPE_DOCUMENT;
 
     if (!browsingContext) {
       debug(`[process-switch]: no BrowsingContext - ignoring`);
@@ -2648,7 +2643,7 @@ var SessionStoreInternal = {
 
     let topDocShell = topBC.embedderElement.ownerGlobal.docShell;
     let { useRemoteSubframes } = topDocShell.QueryInterface(Ci.nsILoadContext);
-    if (!useRemoteSubframes && cp != Ci.nsIContentPolicy.TYPE_DOCUMENT) {
+    if (!useRemoteSubframes && isSubframe) {
       debug(`[process-switch]: remote subframes disabled - ignoring`);
       return;
     }

netwerk/base/LoadInfo.cpp

@@ -1055,6 +1055,14 @@ LoadInfo::GetFrameBrowsingContextID(uint64_t* aResult) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+LoadInfo::GetTargetBrowsingContextID(uint64_t* aResult) {
+  return (nsILoadInfo::GetExternalContentPolicyType() ==
+          nsIContentPolicy::TYPE_SUBDOCUMENT)
+             ? GetFrameBrowsingContextID(aResult)
+             : GetBrowsingContextID(aResult);
+}
+
 NS_IMETHODIMP
 LoadInfo::GetBrowsingContext(dom::BrowsingContext** aResult) {
   *aResult = BrowsingContext::Get(mBrowsingContextID).take();
@@ -1067,6 +1075,14 @@ LoadInfo::GetFrameBrowsingContext(dom::BrowsingContext** aResult) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+LoadInfo::GetTargetBrowsingContext(dom::BrowsingContext** aResult) {
+  uint64_t targetBrowsingContextID = 0;
+  MOZ_ALWAYS_SUCCEEDS(GetTargetBrowsingContextID(&targetBrowsingContextID));
+  *aResult = BrowsingContext::Get(targetBrowsingContextID).take();
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 LoadInfo::GetScriptableOriginAttributes(
     JSContext* aCx, JS::MutableHandle<JS::Value> aOriginAttributes) {

netwerk/base/nsILoadInfo.idl

@@ -662,6 +662,15 @@ interface nsILoadInfo : nsISupports
   [infallible] readonly attribute unsigned long long frameBrowsingContextID;
   readonly attribute BrowsingContext frameBrowsingContext;
 
+  /**
+   * If the element being loaded is a nsFrameLoaderOwner,
+   * `targetBrowsingContext` is the Browsing Context which will contain the
+   * loading document (see `frameBrowsingContext`). Otherwise, it is the
+   * Browsing Context performing the load (see `browsingContext`).
+   */
+  [infallible] readonly attribute unsigned long long targetBrowsingContextID;
+  readonly attribute BrowsingContext targetBrowsingContext;
+
   /**
    * Resets the PrincipalToInherit to a freshly created NullPrincipal
    * which inherits the origin attributes from the loadInfo.

netwerk/protocol/http/nsHttpChannel.cpp

@@ -2687,14 +2687,15 @@ void nsHttpChannel::AssertNotDocumentChannel() {
     return;
   }
 
-  nsContentPolicyType contentPolicy;
-  MOZ_ALWAYS_SUCCEEDS(mLoadInfo->GetExternalContentPolicyType(&contentPolicy));
-  RefPtr<BrowsingContext> bc;
-  if (contentPolicy == CSPService::TYPE_DOCUMENT) {
-    MOZ_ALWAYS_SUCCEEDS(mLoadInfo->GetBrowsingContext(getter_AddRefs(bc)));
-  } else {
-    MOZ_ALWAYS_SUCCEEDS(mLoadInfo->GetFrameBrowsingContext(getter_AddRefs(bc)));
+  auto contentPolicy = mLoadInfo->GetExternalContentPolicyType();
+  if (contentPolicy != nsIContentPolicy::TYPE_DOCUMENT &&
+      contentPolicy != nsIContentPolicy::TYPE_SUBDOCUMENT) {
+    return;
   }
+
+  RefPtr<BrowsingContext> bc;
+  MOZ_ALWAYS_SUCCEEDS(mLoadInfo->GetTargetBrowsingContext(getter_AddRefs(bc)));
+  MOZ_ASSERT(bc);  // It shouldn't be possible.
   if (!bc) {
     return;
   }

toolkit/mozapps/extensions/amContentHandler.jsm

@@ -37,8 +37,7 @@ amContentHandler.prototype = {
 
     let { loadInfo } = aRequest;
     const { triggeringPrincipal } = loadInfo;
-    let browsingContext =
-      loadInfo.frameBrowsingContext || loadInfo.browsingContext;
+    let browsingContext = loadInfo.targetBrowsingContext;
 
     let sourceHost;
     let sourceURL;