Issue #1643 - Part 4: Hook up all the plumbing.

dom/base/ResizeObserver.cpp

@@ -61,7 +61,7 @@ ResizeObserver::Constructor(const GlobalObject& aGlobal,
   }
 
   RefPtr<ResizeObserver> observer = new ResizeObserver(window.forget(), aCb);
-  // TODO: Add the new ResizeObserver to document here in the later patch.
+  document->AddResizeObserver(observer);
 
   return observer.forget();
 }
@@ -86,7 +86,7 @@ ResizeObserver::Observe(Element* aTarget,
     // Per the spec, we need to trigger notification in event loop that
     // contains ResizeObserver observe call even when resize/reflow does
     // not happen.
-    // TODO: Implement the notification scheduling in the later patch.
+    aTarget->OwnerDoc()->ScheduleResizeObserversNotification();
   }
 }
 

dom/base/nsDocument.cpp

@@ -1681,6 +1681,10 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(nsDocument)
       cb.NoteXPCOMChild(mql);
     }
   }
+
+  if (tmp->mResizeObserverController) {
+    tmp->mResizeObserverController->Traverse(cb);
+  }
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(nsDocument)
@@ -1786,6 +1790,10 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsDocument)
   }
 
   tmp->mInUnlinkOrDeletion = false;
+
+  if (tmp->mResizeObserverController) {
+    tmp->mResizeObserverController->Unlink();
+  }
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 nsresult
@@ -11823,6 +11831,24 @@ nsDocument::QuerySelectorAll(const nsAString& aSelector, nsIDOMNodeList **aRetur
   return nsINode::QuerySelectorAll(aSelector, aReturn);
 }
 
+void
+nsDocument::AddResizeObserver(ResizeObserver* aResizeObserver)
+{
+  if (!mResizeObserverController) {
+    mResizeObserverController = MakeUnique<ResizeObserverController>(this);
+  }
+
+  mResizeObserverController->AddResizeObserver(aResizeObserver);
+}
+
+void
+nsDocument::ScheduleResizeObserversNotification() const
+{
+  if (mResizeObserverController) {
+    mResizeObserverController->ScheduleNotification();
+  }
+}
+
 already_AddRefed<nsIDocument>
 nsIDocument::Constructor(const GlobalObject& aGlobal,
                          ErrorResult& rv)

dom/base/nsDocument.h

@@ -60,6 +60,7 @@
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/PendingAnimationTracker.h"
 #include "mozilla/dom/DOMImplementation.h"
+#include "mozilla/dom/ResizeObserverController.h"
 #include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/StyleSheetList.h"
 #include "nsDataHashtable.h"
@@ -1024,6 +1025,10 @@ public:
 
   virtual void UnblockDOMContentLoaded() override;
 
+  void AddResizeObserver(mozilla::dom::ResizeObserver* aResizeObserver) override;
+
+  void ScheduleResizeObserversNotification() const override;
+
 protected:
   friend class nsNodeUtils;
   friend class nsDocumentOnStack;
@@ -1160,6 +1165,9 @@ protected:
 
   nsTArray<nsIObserver*> mCharSetObservers;
 
+  mozilla::UniquePtr<mozilla::dom::ResizeObserverController>
+    mResizeObserverController;
+
   PLDHashTable *mSubDocuments;
 
   // Array of owning references to all children

dom/base/nsIDocument.h

@@ -153,6 +153,7 @@ class ProcessingInstruction;
 class Promise;
 class Selection;
 class ScriptLoader;
+class ResizeObserver;
 class StyleSheetList;
 class SVGDocument;
 class SVGSVGElement;
@@ -2853,6 +2854,10 @@ public:
 
   bool ModuleScriptsEnabled();
 
+  virtual void AddResizeObserver(mozilla::dom::ResizeObserver* aResizeObserver) = 0;
+
+  virtual void ScheduleResizeObserversNotification() const = 0;
+
 protected:
   bool GetUseCounter(mozilla::UseCounter aUseCounter)
   {

layout/base/nsPresShell.cpp

@@ -9060,6 +9060,11 @@ PresShell::DidDoReflow(bool aInterruptible)
     docShell->NotifyReflowObservers(aInterruptible, mLastReflowStart, now);
   }
 
+  // Notify resize observers on reflow.
+  if (!mPresContext->HasPendingInterrupt()) {
+    mDocument->ScheduleResizeObserversNotification();
+  }
+
   if (sSynthMouseMove) {
     SynthesizeMouseMove(false);
   }