Bug 1603889 - Remove AppWindow::GetContentScrollbarVisibility. r=smaug

There's only one test that can potentially rely on this, and still passes
with this patch:

  toolkit/components/windowwatcher/test/browser_new_content_window_chromeflags.js

More to the point, this doesn't work with e10s whatsoever already, and seems
content cannot change the scrollbar visibility anymore, and chrome code doesn't
do it either.

Depends on D57182

Differential Revision: https://phabricator.services.mozilla.com/D57184

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

Author: emilio

xpfe/appshell/AppWindow.cpp

@@ -432,19 +432,6 @@ NS_IMETHODIMP AppWindow::SetZLevel(uint32_t aLevel) {
 NS_IMETHODIMP AppWindow::GetChromeFlags(uint32_t* aChromeFlags) {
   NS_ENSURE_ARG_POINTER(aChromeFlags);
   *aChromeFlags = mChromeFlags;
-  /* mChromeFlags is kept up to date, except for scrollbar visibility.
-     That can be changed directly by the content DOM window, which
-     doesn't know to update the chrome window. So that we must check
-     separately. */
-
-  // however, it's pointless to ask if the window isn't set up yet
-  if (!mChromeLoaded) return NS_OK;
-
-  if (GetContentScrollbarVisibility())
-    *aChromeFlags |= nsIWebBrowserChrome::CHROME_SCROLLBARS;
-  else
-    *aChromeFlags &= ~nsIWebBrowserChrome::CHROME_SCROLLBARS;
-
   return NS_OK;
 }
 
@@ -2441,20 +2428,6 @@ void AppWindow::SetContentScrollbarVisibility(bool aVisible) {
   nsContentUtils::SetScrollbarsVisibility(contentWin->GetDocShell(), aVisible);
 }
 
-bool AppWindow::GetContentScrollbarVisibility() {
-  // This code already exists in dom/src/base/nsBarProp.cpp, but we can't safely
-  // get to that from here as this function is called while the DOM window is
-  // being set up, and we need the DOM window to get to that code.
-  //
-  // FIXME(emilio): This doesn't work at all for e10s or anything like that,
-  // it's likely that nobody is relying on this function.
-  if (nsCOMPtr<nsIDocShell> ds = do_QueryInterface(mPrimaryContentShell)) {
-    return nsDocShell::Cast(ds)->ScrollbarPreference() != ScrollbarPreference::Never;
-  }
-
-  return true;
-}
-
 // during spinup, attributes that haven't been loaded yet can't be dirty
 void AppWindow::PersistentAttributesDirty(uint32_t aDirtyFlags) {
   mPersistentAttributesDirty |= aDirtyFlags & mPersistentAttributesMask;
@@ -2473,8 +2446,8 @@ void AppWindow::ApplyChromeFlags() {
     // So just don't do these until mChromeLoaded is true.
 
     // Scrollbars have their own special treatment.
-    SetContentScrollbarVisibility(
-        mChromeFlags & nsIWebBrowserChrome::CHROME_SCROLLBARS ? true : false);
+    SetContentScrollbarVisibility(mChromeFlags &
+                                  nsIWebBrowserChrome::CHROME_SCROLLBARS);
   }
 
   /* the other flags are handled together. we have style rules

xpfe/appshell/AppWindow.h

@@ -243,7 +243,6 @@ class AppWindow final : public nsIBaseWindow,
   void PlaceWindowLayersBehind(uint32_t aLowLevel, uint32_t aHighLevel,
                                nsIAppWindow* aBehind);
   void SetContentScrollbarVisibility(bool aVisible);
-  bool GetContentScrollbarVisibility();
   void PersistentAttributesDirty(uint32_t aDirtyFlags);
   nsresult GetTabCount(uint32_t* aResult);