CC AnimationHost: Fix ProgrammaticScrollAnimator detach scope.

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index e2ef7303294dd26393e100e322063606a4ee2ed1..860224b94d8e1acc5618bab5231405385a6964e1 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -2685,6 +2685,9 @@ void WebViewImpl::willCloseLayerTreeView()
         m_linkHighlightsTimeline.clear();
     }
 
+    if (page())
+        page()->willCloseLayerTreeView();
+
     setRootGraphicsLayer(nullptr);
     m_layerTreeView = nullptr;
 }