Fullscreen windows at startup

We don't want the browser chrome showing on heads-up displays.

src/marionette/message.rs

@@ -117,4 +117,6 @@ pub enum Command {
     NewWindow,
     #[serde(rename = "WebDriver:SwitchToWindow")]
     SwitchToWindow(SwitchToWindowParams),
+    #[serde(rename = "WebDriver:FullscreenWindow")]
+    FullscreenWindow,
 }

src/marionette/mod.rs

@@ -183,6 +183,13 @@ impl Marionette {
         Ok(())
     }
 
+    pub async fn fullscreen(&mut self) -> Result<(), CommandError> {
+        let res: serde_json::Value =
+            self.conn.send_message(Command::FullscreenWindow).await?.unwrap();
+        debug!("Received message: {:?}", res);
+        Ok(())
+    }
+
     pub async fn get_title(&mut self) -> Result<String, CommandError> {
         let res: GetTitleResponse =
             self.conn.send_message(Command::GetTitle).await?.unwrap();

src/session.rs

@@ -143,7 +143,10 @@ impl Session {
             if window.is_none() {
                 window = Some(self.marionette.new_window().await?);
             }
-            windowmap.insert(monitor.name, window.take().unwrap());
+            let w = window.take().unwrap();
+            self.marionette.switch_to_window(w.clone(), false).await?;
+            self.marionette.fullscreen().await?;
+            windowmap.insert(monitor.name, w);
         }
         trace!("Built window map: {:?}", windowmap);
         Ok(windowmap)