fix build on linux

crates/tauri-runtime-cef/src/cef_webview.rs

@@ -6,6 +6,9 @@ mod macos;
 #[cfg(windows)]
 mod windows;
 
+#[cfg(target_os = "linux")]
+mod linux;
+
 #[derive(Clone)]
 pub enum CefWebview {
   BrowserView(cef::BrowserView),

crates/tauri-runtime-cef/src/cef_webview/linux.rs

@@ -0,0 +1,33 @@
+use cef::*;
+
+use crate::cef_webview::CefBrowserExt;
+
+impl CefBrowserExt for cef::Browser {
+  fn bounds(&self) -> cef::Rect {
+    todo!()
+  }
+
+  fn set_bounds(&self, rect: Option<&cef::Rect>) {
+    todo!()
+  }
+
+  fn scale_factor(&self) -> f64 {
+    todo!()
+  }
+
+  fn set_background_color(&self, color: cef::Color) {
+    // TODO:
+  }
+
+  fn set_visible(&self, visible: i32) {
+    todo!()
+  }
+
+  fn close(&self) {
+    todo!()
+  }
+
+  fn set_parent(&self, parent: &cef::Window) {
+    todo!()
+  }
+}