[DevTools] Destroy agents on detach.

third_party/WebKit/Source/web/InspectorOverlay.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 571 matching lines @@
     if (m_overlayPage) {
         m_overlayPage->willBeDestroyed();
         m_overlayPage.clear();
         m_overlayChromeClient.clear();
     }
     m_resizeTimerActive = false;
     m_pausedInDebuggerMessage = String();
     m_inspectMode = InspectorDOMAgent::NotSearching;
     m_timer.stop();
     hideHighlight();
+
+    m_debuggerAgent.clear();
+    m_domAgent.clear();
+    m_cssAgent.clear();
+    m_overlayHost->setListener(nullptr);
 }
 
 void InspectorOverlay::overlayResumed()
 {
     if (m_debuggerAgent) {
         ErrorString error;
         m_debuggerAgent->resume(&error);
     }
 }
 
@@ skipping 172 matching lines @@
 
 void InspectorOverlay::initializeLayoutEditorIfNeeded(Node* node)
 {
     if (m_inspectMode != InspectorDOMAgent::ShowLayoutEditor || !node || !node->isElementNode() || !node->ownerDocument()->isActive())
         return;
     m_layoutEditor = LayoutEditor::create(toElement(node), m_cssAgent, m_domAgent, &overlayMainFrame()->script());
     toChromeClientImpl(m_webViewImpl->page()->chromeClient()).setCursorOverridden(true);
 }
 
 } // namespace blink