Bug 1411754: Rename PresShell::DestroyFramesFor to DestroyFramesForAndRestyle. r=mats

I'm drive-by removing the comment about the frame tree state because I looked
into it, and the answer is: we properly restore it.

The gotcha is that we retain it too much, indeed, we retain it enough that it
can leak. See bug 1397239.

MozReview-Commit-ID: LP6bXkduEZ4

--HG--
extra : rebase_source : f7e18fc35e48b75c07fcc84b939614d379926828

dom/base/Element.cpp

@@ -1169,7 +1169,7 @@ Element::CreateShadowRoot(ErrorResult& aError)
 
   if (nsIDocument* doc = GetComposedDoc()) {
     if (nsIPresShell* shell = doc->GetShell()) {
-      shell->DestroyFramesFor(this);
+      shell->DestroyFramesForAndRestyle(this);
       MOZ_ASSERT(!shell->FrameManager()->GetDisplayContentsStyleFor(this));
     }
   }

dom/base/ShadowRoot.cpp

@@ -267,8 +267,7 @@ ShadowRoot::DistributionChanged()
     return;
   }
 
-  // FIXME(emilio): Rename this to DestroyFramesForAndRestyle?
-  shell->DestroyFramesFor(host);
+  shell->DestroyFramesForAndRestyle(host);
 }
 
 const HTMLContentElement*
@@ -513,7 +512,7 @@ ShadowRoot::AttributeChanged(nsIDocument* aDocument,
     return;
   }
 
-  shell->DestroyFramesFor(aElement);
+  shell->DestroyFramesForAndRestyle(aElement);
 }
 
 bool

dom/xbl/nsXBLService.cpp

@@ -126,7 +126,7 @@ public:
     // since if the binding fetch fails then we don't want to destroy the
     // frames.
     if (nsIPresShell* shell = doc->GetShell()) {
-      shell->DestroyFramesFor(mBoundElement->AsElement());
+      shell->DestroyFramesForAndRestyle(mBoundElement->AsElement());
     }
     MOZ_ASSERT(!mBoundElement->GetPrimaryFrame());
   }

layout/base/PresShell.cpp

@@ -2922,7 +2922,7 @@ PresShell::CancelAllPendingReflows()
 }
 
 void
-PresShell::DestroyFramesFor(Element* aElement)
+PresShell::DestroyFramesForAndRestyle(Element* aElement)
 {
   MOZ_ASSERT(aElement);
   NS_ENSURE_TRUE_VOID(mPresContext);
@@ -2940,21 +2940,15 @@ PresShell::DestroyFramesFor(Element* aElement)
   bool didReconstruct = fc->DestroyFramesFor(aElement);
   fc->EndUpdate();
 
-  // XXXmats doesn't frame state need to be restored in this case?
-  if (!didReconstruct) {
-    PostRecreateFramesFor(aElement);
-  }
+  auto changeHint = didReconstruct
+    ? nsChangeHint(0)
+    : nsChangeHint_ReconstructFrame;
 
-  // NOTE(emilio): This is needed to force also a full subtree restyle for the
-  // content (in Stylo, where the existence of frames != the existence of
-  // styles).
-  //
-  // It's a bit out of place in a function called DestroyFramesFor,
-  // however the two only callers of this code really need this (given they
-  // shuffle the flattened tree around), and this avoids exposing additional
-  // APIs on the pres shell.
+  // NOTE(emilio): eRestyle_Subtree is needed to force also a full subtree
+  // restyle for the content (in Stylo, where the existence of frames != the
+  // existence of styles).
   mPresContext->RestyleManager()->PostRestyleEvent(
-    aElement, eRestyle_Subtree, nsChangeHint(0));
+    aElement, eRestyle_Subtree, changeHint);
 
   --mChangeNestCount;
 }

layout/base/PresShell.h

@@ -131,7 +131,7 @@ public:
   virtual bool IsSafeToFlush() const override;
   virtual void DoFlushPendingNotifications(mozilla::FlushType aType) override;
   virtual void DoFlushPendingNotifications(mozilla::ChangesToFlush aType) override;
-  virtual void DestroyFramesFor(mozilla::dom::Element* aElement) override;
+  virtual void DestroyFramesForAndRestyle(mozilla::dom::Element* aElement) override;
 
   /**
    * Post a callback that should be handled after reflow has finished.

layout/base/nsIPresShell.h

@@ -528,7 +528,7 @@ public:
    *
    * Note that this may destroy frames for an ancestor instead.
    */
-  virtual void DestroyFramesFor(mozilla::dom::Element* aElement) = 0;
+  virtual void DestroyFramesForAndRestyle(mozilla::dom::Element* aElement) = 0;
 
   void PostRecreateFramesFor(mozilla::dom::Element* aElement);
   void RestyleForAnimation(mozilla::dom::Element* aElement,