Bug 1330375 - P1: Helper for checking for ancestor of dirty reflow root. r=emilio,heycam,rwood

Including refactoring mDirtyRoots into nsIPresShell to avoid virtual call.

MozReview-Commit-ID: KxST8FMsZl9

--HG--
extra : rebase_source : 1be1a8065815bb1e67293c7839c6e9189fc693bc

layout/base/PresShell.cpp

@@ -4563,6 +4563,27 @@ PresShell::NotifyCounterStylesAreDirty()
   mFrameConstructor->NotifyCounterStylesAreDirty();
 }
 
+bool
+nsIPresShell::FrameIsAncestorOfDirtyRoot(nsIFrame* aFrame) const
+{
+  MOZ_ASSERT(aFrame);
+
+  // Look for a path from any dirty roots to aFrame, following GetParent().
+  // This check mirrors what FrameNeedsReflow() would have done if the reflow
+  // root didn't get in the way.
+  for (nsIFrame* dirtyFrame : mDirtyRoots) {
+    while (dirtyFrame) {
+      if (dirtyFrame == aFrame) {
+        return true;
+      }
+
+      dirtyFrame = dirtyFrame->GetParent();
+    }
+  }
+
+  return false;
+}
+
 void
 PresShell::ReconstructFrames()
 {

layout/base/PresShell.h

@@ -784,9 +784,6 @@ private:
   // we finish reflowing mCurrentReflowRoot.
   nsTHashtable<nsPtrHashKey<nsIFrame> > mFramesToDirty;
 
-  // Reflow roots that need to be reflowed.
-  nsTArray<nsIFrame*> mDirtyRoots;
-
   nsTArray<nsAutoPtr<DelayedEvent> > mDelayedEvents;
 private:
   nsIFrame* mCurrentEventFrame;

layout/base/nsIPresShell.h

@@ -503,6 +503,8 @@ public:
 
   virtual void NotifyCounterStylesAreDirty() = 0;
 
+  bool FrameIsAncestorOfDirtyRoot(nsIFrame* aFrame) const;
+
   /**
    * Destroy the frames for aElement, and reconstruct them asynchronously if
    * needed.
@@ -1761,6 +1763,9 @@ protected:
   // A hash table of heap allocated weak frames.
   nsTHashtable<nsPtrHashKey<WeakFrame>> mWeakFrames;
 
+  // Reflow roots that need to be reflowed.
+  nsTArray<nsIFrame*> mDirtyRoots;
+
 #ifdef MOZ_GECKO_PROFILER
   // These two fields capture call stacks of any changes that require a restyle
   // or a reflow. Only the first change per restyle / reflow is recorded (the