--- a/gfx/layers/apz/test/gtest/APZCBasicTester.h
+++ b/gfx/layers/apz/test/gtest/APZCBasicTester.h
@@ -25,16 +25,17 @@ protected:
   {
     gfxPrefs::GetSingleton();
     APZThreadUtils::SetThreadAssertionsEnabled(false);
     APZThreadUtils::SetControllerThread(MessageLoop::current());
 
     tm = new TestAPZCTreeManager(mcc);
     apzc = new TestAsyncPanZoomController(0, mcc, tm, mGestureBehavior);
     apzc->SetFrameMetrics(TestFrameMetrics());
+    apzc->GetScrollMetadata().SetIsLayersIdRoot(true);
   }
 
   /**
    * Get the APZC's scroll range in CSS pixels.
    */
   CSSRect GetScrollRange() const
   {
     const FrameMetrics& metrics = apzc->GetFrameMetrics();

--- a/gfx/layers/apz/test/gtest/APZCTreeManagerTester.h
+++ b/gfx/layers/apz/test/gtest/APZCTreeManagerTester.h
@@ -169,16 +169,17 @@ protected:
     // LayerID                     0 1
     nsIntRegion layerVisibleRegion[] = {
       nsIntRegion(IntRect(0,0,100,100)),
       nsIntRegion(IntRect(0,0,100,100)),
     };
     root = CreateLayerTree(layerTreeSyntax, layerVisibleRegion, nullptr, lm, layers);
     SetScrollableFrameMetrics(layers[0], FrameMetrics::START_SCROLL_ID);
     SetScrollableFrameMetrics(layers[1], FrameMetrics::START_SCROLL_ID + 1);
+    SetScrollHandoff(layers[1], layers[0]);
 
     // Make layers[1] the root content
     ScrollMetadata childMetadata = layers[1]->GetScrollMetadata(0);
     childMetadata.GetMetrics().SetIsRootContent(true);
     layers[1]->SetScrollMetadata(childMetadata);
 
     // Both layers are fully dispatch-to-content
     EventRegions regions;

--- a/gfx/layers/apz/test/gtest/TestEventRegions.cpp
+++ b/gfx/layers/apz/test/gtest/TestEventRegions.cpp
@@ -140,18 +140,19 @@ protected:
     Matrix4x4 layerTransforms[] = {
       Matrix4x4(),
       Matrix4x4::Translation(50, 0, 0),
       Matrix4x4(),
       Matrix4x4(),
     };
     root = CreateLayerTree(layerTreeSyntax, layerVisibleRegions, layerTransforms, lm, layers);
 
-    SetScrollableFrameMetrics(layers[2], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 10, 10));
-    SetScrollableFrameMetrics(layers[3], FrameMetrics::START_SCROLL_ID + 2, CSSRect(0, 0, 100, 100));
+    SetScrollableFrameMetrics(layers[2], FrameMetrics::START_SCROLL_ID, CSSRect(0, 0, 10, 10));
+    SetScrollableFrameMetrics(layers[3], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 100, 100));
+    SetScrollHandoff(layers[3], layers[2]);
 
     EventRegions regions(nsIntRegion(IntRect(0, 0, 10, 10)));
     layers[2]->SetEventRegions(regions);
     regions.mHitRegion = nsIntRegion(IntRect(0, 0, 100, 100));
     regions.mDispatchToContentHitRegion = nsIntRegion(IntRect(0, 0, 100, 100));
     layers[3]->SetEventRegions(regions);
 
     registration = MakeUnique<ScopedLayerTreeRegistration>(manager, 0, root, mcc);

--- a/gfx/layers/apz/test/gtest/TestScrollHandoff.cpp
+++ b/gfx/layers/apz/test/gtest/TestScrollHandoff.cpp
@@ -54,20 +54,23 @@ protected:
     nsIntRegion layerVisibleRegion[] = {
       nsIntRegion(IntRect(0, 0, 100, 100)),  // root
       nsIntRegion(IntRect(0, 0, 100, 50)),   // scrolling parent 1
       nsIntRegion(IntRect(0, 0, 100, 50)),   // scrolling child 1
       nsIntRegion(IntRect(0, 50, 100, 50)),  // scrolling parent 2
       nsIntRegion(IntRect(0, 50, 100, 50))   // scrolling child 2
     };
     root = CreateLayerTree(layerTreeSyntax, layerVisibleRegion, nullptr, lm, layers);
-    SetScrollableFrameMetrics(layers[1], FrameMetrics::START_SCROLL_ID, CSSRect(0, 0, 100, 100));
-    SetScrollableFrameMetrics(layers[2], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 100, 100));
-    SetScrollableFrameMetrics(layers[3], FrameMetrics::START_SCROLL_ID + 2, CSSRect(0, 50, 100, 100));
-    SetScrollableFrameMetrics(layers[4], FrameMetrics::START_SCROLL_ID + 3, CSSRect(0, 50, 100, 100));
+    SetScrollableFrameMetrics(layers[0], FrameMetrics::START_SCROLL_ID, CSSRect(0, 0, 100, 100));
+    SetScrollableFrameMetrics(layers[1], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 100, 100));
+    SetScrollableFrameMetrics(layers[2], FrameMetrics::START_SCROLL_ID + 2, CSSRect(0, 0, 100, 100));
+    SetScrollableFrameMetrics(layers[3], FrameMetrics::START_SCROLL_ID + 3, CSSRect(0, 50, 100, 100));
+    SetScrollableFrameMetrics(layers[4], FrameMetrics::START_SCROLL_ID + 4, CSSRect(0, 50, 100, 100));
+    SetScrollHandoff(layers[1], layers[0]);
+    SetScrollHandoff(layers[3], layers[0]);
     SetScrollHandoff(layers[2], layers[1]);
     SetScrollHandoff(layers[4], layers[3]);
     registration = MakeUnique<ScopedLayerTreeRegistration>(manager, 0, root, mcc);
     manager->UpdateHitTestingTree(nullptr, root, false, 0, 0);
   }
 
   void CreateScrollgrabLayerTree(bool makeParentScrollable = true) {
     const char* layerTreeSyntax = "c(t)";