Remove dead extensions tracking code.

extensions/renderer/dispatcher.h

Index: extensions/renderer/dispatcher.h
diff --git a/extensions/renderer/dispatcher.h b/extensions/renderer/dispatcher.h
index b960bef335a44d0aa817cb4de856cf3510e0fe5d..2e50fcf90343447e901944ae370e1599d2cab599 100644
--- a/extensions/renderer/dispatcher.h
+++ b/extensions/renderer/dispatcher.h
@@ -149,8 +149,6 @@ class Dispatcher : public content::RenderThreadObserver,
                                      RequestSender* request_sender,
                                      V8SchemaRegistry* v8_schema_registry);
 
-  bool WasWebRequestUsedBySomeExtensions() const { return webrequest_used_; }
-
  private:
   // The RendererPermissionsPolicyDelegateTest.CannotScriptWebstore test needs
   // to call the OnActivateExtension IPCs.
@@ -202,7 +200,7 @@ class Dispatcher : public content::RenderThreadObserver,
       const std::vector<std::string>& extension_ids,
       bool update_origin_whitelist,
       int tab_id);
-  void OnUsingWebRequestAPI(bool webrequest_used);
+
   void OnSetActivityLoggingEnabled(bool enabled);
 
   // UserScriptSetManager::Observer implementation.
@@ -310,9 +308,6 @@ class Dispatcher : public content::RenderThreadObserver,
   ScopedObserver<UserScriptSetManager, UserScriptSetManager::Observer>
       user_script_set_manager_observer_;
 
-  // Status of webrequest usage.
-  bool webrequest_used_;
-
   // Whether or not extension activity is enabled.
   bool activity_logging_enabled_;