fix: FTBFS when building with enable_plugins = false (#44003)

* fix: do not build electron_plugin_info_host_impl.cc when plugins are disabled

it fails to build from source with this error:

../../content/public/browser/plugin_service.h:17:2: error: "Plugins should be enabled"
   17 | #error "Plugins should be enabled"

* fix: FTBFS in printing_utils.cc when ENABLE_PDF is false

* fixup! fix: do not build electron_plugin_info_host_impl.cc when plugins are disabled

fix BUILD.gn linting

shell/browser/electron_browser_client.cc

@@ -1458,6 +1458,7 @@ void ElectronBrowserClient::
                                                       render_frame_host);
           },
           &render_frame_host));
+#if BUILDFLAG(ENABLE_PLUGINS)
   associated_registry.AddInterface<mojom::ElectronPluginInfoHost>(
       base::BindRepeating(
           [](content::RenderFrameHost* render_frame_host,
@@ -1468,6 +1469,7 @@ void ElectronBrowserClient::
                 std::move(receiver));
           },
           &render_frame_host));
+#endif
 #if BUILDFLAG(ENABLE_PRINTING)
   associated_registry.AddInterface<printing::mojom::PrintManagerHost>(
       base::BindRepeating(