Gracefully handle a self-referential opener in frame swap.

third_party/WebKit/Source/web/OpenedFrameTracker.cpp

Index: third_party/WebKit/Source/web/OpenedFrameTracker.cpp
diff --git a/third_party/WebKit/Source/web/OpenedFrameTracker.cpp b/third_party/WebKit/Source/web/OpenedFrameTracker.cpp
index bd0181391b5d3058672a7cb313c2cc45e90f8d1b..f64572675156cb5da46949e580aa2374fa885055 100644
--- a/third_party/WebKit/Source/web/OpenedFrameTracker.cpp
+++ b/third_party/WebKit/Source/web/OpenedFrameTracker.cpp
@@ -18,7 +18,7 @@ OpenedFrameTracker::~OpenedFrameTracker()
 {
 #if !ENABLE(OILPAN)
     // Oilpan takes care of clearing weak m_opener fields during GC.
-    updateOpener(0);
+    transferTo(nullptr);
 #endif
 }
 
@@ -37,11 +37,11 @@ void OpenedFrameTracker::remove(WebFrame* frame)
     m_openedFrames.remove(frame);
 }
 
-void OpenedFrameTracker::updateOpener(WebFrame* frame)
+void OpenedFrameTracker::transferTo(WebFrame* opener)
 {
-    HashSet<WebFrame*>::iterator end = m_openedFrames.end();
-    for (HashSet<WebFrame*>::iterator it = m_openedFrames.begin(); it != end; ++it)
-        (*it)->m_opener = frame;
+    HashSet<WebFrame*> frames(m_openedFrames);

[alexmos, 2015/10/27 19:09:51]

nit: is it worth adding a comment about why the copy is necessary here? (because
setOpener modifies m_openedFrames, right?)

[dcheng, 2015/10/27 19:11:16]

Yeah, probably worth commenting. I'll add it and CQ it after lunch.

+    for (WebFrame* frame : frames)
+        frame->setOpener(opener);
 }
 
 template <typename VisitorDispatcher>