Bug 1526958 - Cache dom::TouchEvent::PrefEnabled in nsDisplayListBuilder r=mattwoodrow

Differential Revision: https://phabricator.services.mozilla.com/D20326

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

layout/generic/nsFrame.cpp

@@ -10775,11 +10775,7 @@ CompositorHitTestInfo nsIFrame::GetCompositorHitTestInfo(
     }
   }
 
-  nsIDocShell* docShell = nullptr;
-  if (PresShell()->GetDocument()) {
-    docShell = PresShell()->GetDocument()->GetDocShell();
-  }
-  if (dom::TouchEvent::PrefEnabled(docShell)) {
+  if (aBuilder->IsTouchEventPrefEnabledDoc()) {
     // Inherit the touch-action flags from the parent, if there is one. We do
     // this because of how the touch-action on a frame combines the touch-action
     // from ancestor DOM elements. Refer to the documentation in

layout/painting/nsDisplayList.cpp

@@ -25,6 +25,7 @@
 #include "mozilla/dom/ServiceWorkerRegistrar.h"
 #include "mozilla/dom/ServiceWorkerRegistration.h"
 #include "mozilla/dom/SVGElement.h"
+#include "mozilla/dom/TouchEvent.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/layers/PLayerTransaction.h"
 #include "mozilla/ShapeUtils.h"
@@ -1422,12 +1423,14 @@ void nsDisplayListBuilder::EnterPresShell(nsIFrame* aReferenceFrame,
           : nullptr;
 
   nsPresContext* pc = aReferenceFrame->PresContext();
-  nsCOMPtr<nsIDocShell> docShell = pc->GetDocShell();
+  mIsInChromePresContext = pc->IsChrome();
+  nsIDocShell* docShell = pc->GetDocShell();
+
   if (docShell) {
     docShell->GetWindowDraggingAllowed(&mWindowDraggingAllowed);
   }
 
-  mIsInChromePresContext = pc->IsChrome();
+  state->mTouchEventPrefEnabledDoc = dom::TouchEvent::PrefEnabled(docShell);
 
   if (!buildCaret) {
     return;
@@ -1518,11 +1521,11 @@ void nsDisplayListBuilder::LeavePresShell(nsIFrame* aReferenceFrame,
   }
 
   ResetMarkedFramesForDisplayList(aReferenceFrame);
-  mPresShellStates.SetLength(mPresShellStates.Length() - 1);
+  mPresShellStates.RemoveLastElement();
 
   if (!mPresShellStates.IsEmpty()) {
     nsPresContext* pc = CurrentPresContext();
-    nsCOMPtr<nsIDocShell> docShell = pc->GetDocShell();
+    nsIDocShell* docShell = pc->GetDocShell();
     if (docShell) {
       docShell->GetWindowDraggingAllowed(&mWindowDraggingAllowed);
     }

layout/painting/nsDisplayList.h

@@ -742,6 +742,10 @@ class nsDisplayListBuilder {
     return CurrentPresShellState()->mInsidePointerEventsNoneDoc;
   }
 
+  bool IsTouchEventPrefEnabledDoc() {
+    return CurrentPresShellState()->mTouchEventPrefEnabledDoc;
+  }
+
   bool GetAncestorHasApzAwareEventHandler() const {
     return mAncestorHasApzAwareEventHandler;
   }
@@ -1833,6 +1837,7 @@ class nsDisplayListBuilder {
     // in the document, and is set when we enter a subdocument for a pointer-
     // events:none frame.
     bool mInsidePointerEventsNoneDoc;
+    bool mTouchEventPrefEnabledDoc;
     nsIFrame* mPresShellIgnoreScrollFrame;
   };