Bug 1580565 - Part 3: Simplify API for creating independent BCs, r=farre

There were previously a number of different APIs for creating BrowsingContext
instances. This simplifies them into two major cases: "CreateDetached", which
allows for creating BrowsingContexts which are related to other
BrowsingContexts, and "CreateIndependent" which creates new, fully unrelated,
browsing contexts.

Differential Revision: https://phabricator.services.mozilla.com/D71237

docshell/base/BrowsingContext.cpp

@@ -261,19 +261,11 @@ already_AddRefed<BrowsingContext> BrowsingContext::CreateDetached(
   return context.forget();
 }
 
-already_AddRefed<BrowsingContext> BrowsingContext::Create(
-    BrowsingContext* aParent, BrowsingContext* aOpener, const nsAString& aName,
+already_AddRefed<BrowsingContext> BrowsingContext::CreateIndependent(
     Type aType) {
-  RefPtr<BrowsingContext> bc(CreateDetached(aParent, aOpener, aName, aType));
-  bc->EnsureAttached();
-  return bc.forget();
-}
-
-already_AddRefed<BrowsingContext> BrowsingContext::CreateWindowless(
-    BrowsingContext* aParent, BrowsingContext* aOpener, const nsAString& aName,
-    Type aType) {
-  RefPtr<BrowsingContext> bc(CreateDetached(aParent, aOpener, aName, aType));
-  bc->mWindowless = true;
+  RefPtr<BrowsingContext> bc(
+      CreateDetached(nullptr, nullptr, EmptyString(), aType));
+  bc->mWindowless = bc->IsContent();
   bc->EnsureAttached();
   return bc.forget();
 }

docshell/base/BrowsingContext.h

@@ -166,28 +166,27 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
     return GetFromWindow(aProxy);
   }
 
-  // Create a brand-new BrowsingContext object.
-  static already_AddRefed<BrowsingContext> Create(BrowsingContext* aParent,
-                                                  BrowsingContext* aOpener,
-                                                  const nsAString& aName,
-                                                  Type aType);
+  // Create a brand-new toplevel BrowsingContext with no relationships to other
+  // BrowsingContexts, and which is not embedded within any <browser> or frame
+  // element.
+  //
+  // This BrowsingContext is immediately attached, and cannot have LoadContext
+  // flags customized unless it is of `Type::Chrome`.
+  //
+  // The process which created this BrowsingContext is responsible for detaching
+  // it.
+  static already_AddRefed<BrowsingContext> CreateIndependent(Type aType);
 
-  // Same as the above, but does not immediately attach the browsing context.
+  // Create a brand-new BrowsingContext object, but does not immediately attach
+  // it. State such as OriginAttributes and PrivateBrowsingId may be customized
+  // to configure the BrowsingContext before it is attached.
+  //
   // `EnsureAttached()` must be called before the BrowsingContext is used for a
   // DocShell, BrowserParent, or BrowserBridgeChild.
   static already_AddRefed<BrowsingContext> CreateDetached(
       BrowsingContext* aParent, BrowsingContext* aOpener,
       const nsAString& aName, Type aType);
 
-  // Same as Create, but for a BrowsingContext which does not belong to a
-  // visible window, and will always be detached by the process that created it.
-  // In contrast, any top-level BrowsingContext created in a content process
-  // using Create() is assumed to belong to a <browser> element in the parent
-  // process, which will be responsible for detaching it.
-  static already_AddRefed<BrowsingContext> CreateWindowless(
-      BrowsingContext* aParent, BrowsingContext* aOpener,
-      const nsAString& aName, Type aType);
-
   void EnsureAttached();
 
   bool EverAttached() const { return mEverAttached; }

layout/printing/nsPrintObject.cpp

@@ -76,9 +76,7 @@ nsresult nsPrintObject::InitAsRootObject(nsIDocShell* aDocShell, Document* aDoc,
     // is detached from any browser window or tab.
 
     // Create a new BrowsingContext to create our DocShell in.
-    RefPtr<BrowsingContext> bc = BrowsingContext::CreateWindowless(
-        /* aParent */ nullptr,
-        /* aOpener */ nullptr, EmptyString(),
+    RefPtr<BrowsingContext> bc = BrowsingContext::CreateIndependent(
         nsDocShell::Cast(aDocShell)->GetBrowsingContext()->GetType());
 
     // Create a container docshell for printing.

xpfe/appshell/AppWindow.cpp

@@ -233,8 +233,7 @@ nsresult AppWindow::Initialize(nsIAppWindow* aParent, nsIAppWindow* aOpener,
   // to pass in the opener window here. The opener is set later, if needed, by
   // nsWindowWatcher.
   RefPtr<BrowsingContext> browsingContext =
-      BrowsingContext::Create(/* aParent */ nullptr, /* aOpener */ nullptr,
-                              EmptyString(), BrowsingContext::Type::Chrome);
+      BrowsingContext::CreateIndependent(BrowsingContext::Type::Chrome);
 
   // Create web shell
   mDocShell = nsDocShell::Create(browsingContext);

xpfe/appshell/nsAppShellService.cpp

@@ -449,8 +449,7 @@ nsAppShellService::CreateWindowlessBrowser(bool aIsChrome,
   NS_ENSURE_SUCCESS(rv, rv);
 
   // Create a BrowsingContext for our windowless browser.
-  RefPtr<BrowsingContext> browsingContext = BrowsingContext::CreateWindowless(
-      nullptr, nullptr, EmptyString(),
+  RefPtr<BrowsingContext> browsingContext = BrowsingContext::CreateIndependent(
       aIsChrome ? BrowsingContext::Type::Chrome
                 : BrowsingContext::Type::Content);