Fixed clip resize for document.rootScroller with inertTopControls

third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp

Index: third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp b/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
index 5d6d6d3fb280d241804e343a125a07cfdbfc5af3..626bba9f8c8e0d56faf9648c5433b1d8bff579e8 100644
--- a/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
@@ -41,6 +41,26 @@ void TopDocumentRootScrollerController::didChangeRootScroller() {
   recomputeGlobalRootScroller();
 }
 
+void TopDocumentRootScrollerController::mainFrameViewResized() {
+  Element* rootScroller = globalRootScroller();
+  if (!rootScroller)
+    return;
+
+  ScrollableArea* area = RootScrollerUtil::scrollableAreaFor(*rootScroller);
+
+  if (!area)
+    return;
+
+  if (PaintLayer* layer = area->layer()) {
+    layer->setNeedsCompositingInputsUpdate();

[bokan, 2016/11/15 00:20:09]

This isn't really a CompositingInputsUpdate, but I need to mark the
CompositedLayerMapping as needsGraphicsLayerUpdate and I don't think there's a
way to do that from PaintLayer. We can't query compositing state at this point
so I can't ask for the CLM.

Is there a right way to do this, or is this ok? Or should I just disable the
compositing query asserts?

+
+    // This is needed if the root scroller is an iframe, since the iframe
+    // doesn't have a scrolling/clip layer, its PLC has a container layer that
+    // needs to be resized instead.
+    layer->compositor()->frameViewDidChangeSize();
+  }
+}
+
 Element* TopDocumentRootScrollerController::findGlobalRootScrollerElement() {
   if (!topDocument())
     return nullptr;