Revert of DevTools: use per-LocalFrame instrumenting agents instead of per-Page ones.

Source/core/inspector/InspectorController.h

Index: Source/core/inspector/InspectorController.h
diff --git a/Source/core/inspector/InspectorController.h b/Source/core/inspector/InspectorController.h
index 4c080094e465aabc266552d4602a15849bd9be43..3de1b0ae1a525b7c58484eff3672f8a99d5a85da 100644
--- a/Source/core/inspector/InspectorController.h
+++ b/Source/core/inspector/InspectorController.h
@@ -137,12 +137,12 @@
     void willAddPageOverlay(const GraphicsLayer*);
     void didRemovePageOverlay(const GraphicsLayer*);
 
-    InstrumentingAgents* instrumentingAgents() { return m_instrumentingAgents.get(); }
-
 private:
     InspectorController(Page*, InspectorClient*);
 
     void initializeDeferredAgents();
+
+    friend InstrumentingAgents* instrumentationForPage(Page*);
 
     RefPtrWillBeMember<InstrumentingAgents> m_instrumentingAgents;
     OwnPtrWillBeMember<InjectedScriptManager> m_injectedScriptManager;
@@ -162,6 +162,7 @@
     RefPtrWillBeMember<InspectorBackendDispatcher> m_inspectorBackendDispatcher;
     InspectorFrontendClient* m_inspectorFrontendClient;
     OwnPtr<InspectorFrontend> m_inspectorFrontend;
+    RawPtrWillBeMember<Page> m_page;
     InspectorClient* m_inspectorClient;
     InspectorAgentRegistry m_agents;
     bool m_isUnderTest;