feat: implement keepAlive message handling for PIP functionality

Author: apades

src/background/docPIP.ts

@@ -74,3 +74,7 @@ onMessage(
 onMessage(WebextEvent.closePIP, () => {
   setDocPIPTabId(null)
 })
+
+onMessage(WebextEvent.keepAlive, () => {
+  console.log('keepAlive')
+})

src/core/WebProvider/DocPIPWebProvider.ts

@@ -256,6 +256,13 @@ canvas{
 }`,
     })
     playerEl.appendChild(docPIPRootStyle)
+
+    const keepAlive = setInterval(() => {
+      sendMessage(WebextEvent.keepAlive, null)
+    }, 1000)
+    this.addOnUnloadFn(() => {
+      clearInterval(keepAlive)
+    })
   }
 
   override close(): void {

src/shared/webextEvent.ts

@@ -22,6 +22,8 @@ enum WebextEvent {
   closePIP = 'closePIP',
 
   reloadPage = 'reloadPage',
+
+  keepAlive = 'keepAlive',
 }
 
 export default WebextEvent