[Panels] Fix favicon crash from using deleted WebContents.

chrome/browser/ui/panels/panel_host.cc

Index: chrome/browser/ui/panels/panel_host.cc
diff --git a/chrome/browser/ui/panels/panel_host.cc b/chrome/browser/ui/panels/panel_host.cc
index a8d7704cc5f8973e5e8e1caa10c491bc7d9ea220..f714045052e6e15f01bb23619c37d9b692d2c548 100644
--- a/chrome/browser/ui/panels/panel_host.cc
+++ b/chrome/browser/ui/panels/panel_host.cc
@@ -203,6 +203,8 @@ void PanelHost::RenderViewGone(base::TerminationStatus status) {
 }
 
 void PanelHost::WebContentsDestroyed(content::WebContents* web_contents) {
+  DCHECK(web_contents == web_contents_.get());
+  web_contents_.reset();

[sky, 2012/10/11 01:03:54]

WebContentsDestroyed is invoked from ~WebContents (well, ~WebContentsImpl). That
means if you get here and web_contents_ is valid you're going to attempt to
delete it again.

If this class owns the WebContents wrapped in web_contents_ and its always
deleting through the scopedptr, this code is unecessary. If someone else is
deleting the WebContents out from under you, then you need a
web_contents_.release() here.

   // Close the panel after we return to the message loop (not immediately,
   // otherwise, it may destroy this object before the stack has a chance
   // to cleanly unwind.)