extensions: Destroy ExtensionMessageFilter on IO thread.

extensions/browser/extension_message_filter.cc

Index: extensions/browser/extension_message_filter.cc
diff --git a/extensions/browser/extension_message_filter.cc b/extensions/browser/extension_message_filter.cc
index e25480dcaf54317d778d4c3e369267d1c4d89f84..f7e794bf7e5a94a2c086cdddd359ec3fc9dc85d6 100644
--- a/extensions/browser/extension_message_filter.cc
+++ b/extensions/browser/extension_message_filter.cc
@@ -31,7 +31,9 @@ ExtensionMessageFilter::ExtensionMessageFilter(int render_process_id,
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 }
 
-ExtensionMessageFilter::~ExtensionMessageFilter() {}
+ExtensionMessageFilter::~ExtensionMessageFilter() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+}
 
 void ExtensionMessageFilter::OverrideThreadForMessage(
     const IPC::Message& message,
@@ -53,6 +55,12 @@ void ExtensionMessageFilter::OverrideThreadForMessage(
   }
 }
 
+void ExtensionMessageFilter::OnDestruct() const {
+  // Destroy the filter on the IO thread since that's where its weak pointers
+  // are being used.
+  BrowserThread::DeleteOnIOThread::Destruct(this);
+}
+
 bool ExtensionMessageFilter::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(ExtensionMessageFilter, message)