Explicitly detach remote window from its frame.

third_party/WebKit/Source/core/frame/RemoteFrame.cpp

Index: third_party/WebKit/Source/core/frame/RemoteFrame.cpp
diff --git a/third_party/WebKit/Source/core/frame/RemoteFrame.cpp b/third_party/WebKit/Source/core/frame/RemoteFrame.cpp
index 88ba74565b4c8961e920dd91f3fc55af2e000ec8..444e796189cb4eaa879abe371b86e5cc018444f1 100644
--- a/third_party/WebKit/Source/core/frame/RemoteFrame.cpp
+++ b/third_party/WebKit/Source/core/frame/RemoteFrame.cpp
@@ -145,6 +145,14 @@ void RemoteFrame::setView(PassRefPtrWillBeRawPtr<RemoteFrameView> view)
     // Oilpan: as RemoteFrameView performs no finalization actions,
     // no explicit dispose() of it needed here. (cf. FrameView::dispose().)
     m_view = view;
+
+    // ... the RemoteDOMWindow will need to be informed of detachment,
+    // as otherwise it will keep a strong reference back to this RemoteFrame.
+    // That combined with wrappers (owned and kept alive by RemoteFrame) keeping
+    // persistent strong references to RemoteDOMWindow will prevent the GCing
+    // of all these objects. Break the cycle by notifying of detachment.
+    if (!m_view)
+        m_domWindow->frameDetached();
 }
 
 void RemoteFrame::createView()