Do FilteringNetworkManager::CheckPermission from new Initialize method.

content/renderer/p2p/port_allocator.h

Index: content/renderer/p2p/port_allocator.h
diff --git a/content/renderer/p2p/port_allocator.h b/content/renderer/p2p/port_allocator.h
index 71a1f6111922ee93e3a3e785e8506b5f7dac4b70..f686b39643e4ded4c49106a74d0095caae073c31 100644
--- a/content/renderer/p2p/port_allocator.h
+++ b/content/renderer/p2p/port_allocator.h
@@ -45,6 +45,9 @@ class P2PPortAllocator : public cricket::BasicPortAllocator {
                    const GURL& origin);
   ~P2PPortAllocator() override;
 
+  // Will also initialize the network manager passed into the constructor.
+  void Initialize() override;
+
  private:
   std::unique_ptr<rtc::NetworkManager> network_manager_;
   scoped_refptr<P2PSocketDispatcher> socket_dispatcher_;