Oilpan: extend tracing over WebFrame trees.

Source/web/WebRemoteFrameImpl.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "web/WebRemoteFrameImpl.h"
 
 #include "core/frame/FrameOwner.h"
 #include "core/frame/RemoteFrame.h"
 #include "core/frame/Settings.h"
@@ skipping 113 matching lines @@
 #if ENABLE(OILPAN)
     , m_selfKeepAlive(this)
 #endif
 {
 }
 
 WebRemoteFrameImpl::~WebRemoteFrameImpl()
 {
 }
 
+#if ENABLE(OILPAN)
 void WebRemoteFrameImpl::trace(Visitor* visitor)
 {
-#if ENABLE(OILPAN)
     visitor->trace(m_frame);
     visitor->trace(m_ownersForChildren);
+    visitor->registerWeakMembers<WebRemoteFrameImpl, &WebRemoteFrameImpl::clearWeakMembers>(this);

[dcheng, 2014/09/29 04:11:45]

Why do we need to forward this through WebRemoteFrameImpl/WebLocalFrameImpl?
Can't WebFrame::traceFrames() register this itself?

[sof, 2014/09/29 06:41:25]

You could do that, but you have to be careful not to re-register the weak
callback each time you call traceFrame(). Having it here provides a clearer
separation & avoidance of that detail.

I didn't like that quirkiness, which is why it is like in the above, but I've
put up a version that moves weak pointer processing to the WebFrame side
instead. Do we want to do this?

+    WebFrame::traceFrames(visitor, this);
+}
 
-    WebFrame::traceChildren(visitor, this);
+void WebRemoteFrameImpl::clearWeakMembers(Visitor* visitor)
+{
+    WebFrame::clearWeakFrames(visitor, this);
+}
 #endif
-}
 
 bool WebRemoteFrameImpl::isWebLocalFrame() const
 {
     return false;
 }
 
 WebLocalFrame* WebRemoteFrameImpl::toWebLocalFrame()
 {
     ASSERT_NOT_REACHED();
     return 0;
@@ skipping 720 matching lines @@
 }
 
 WebRemoteFrameImpl* WebRemoteFrameImpl::fromFrame(RemoteFrame& frame)
 {
     if (!frame.client())
         return 0;
     return static_cast<RemoteFrameClient*>(frame.client())->webFrame();
 }
 
 } // namespace blink