Another attempt at landing this....

chrome/browser/external_tab_container.cc

Index: chrome/browser/external_tab_container.cc
===================================================================
--- chrome/browser/external_tab_container.cc	(revision 27399)
+++ chrome/browser/external_tab_container.cc	(working copy)
@@ -12,6 +12,7 @@
 #include "base/win_util.h"
 #include "chrome/browser/automation/automation_provider.h"
 #include "chrome/browser/browser_window.h"
+#include "chrome/browser/debugger/devtools_manager.h"
 #include "chrome/browser/load_notification_details.h"
 #include "chrome/browser/page_info_window.h"
 #include "chrome/browser/profile.h"
@@ -158,6 +159,11 @@
 void ExternalTabContainer::Uninitialize() {
   registrar_.RemoveAll();
   if (tab_contents_) {
+    RenderViewHost* rvh = tab_contents_->render_view_host();
+    if (rvh && DevToolsManager::GetInstance()) {
+      DevToolsManager::GetInstance()->UnregisterDevToolsClientHostFor(rvh);
+    }
+
     NotificationService::current()->Notify(
         NotificationType::EXTERNAL_TAB_CLOSED,
         Source<NavigationController>(&tab_contents_->controller()),