Change getTabs to getWindows

src/ts/tabs.ts

@@ -1,5 +1,16 @@
-export {getTabs};
+export {getWindows};
 
-function getTabs(callback) {
-	chrome.tabs.query({}, callback);
+let windowCache: chrome.windows.Window[] = [];
+
+/**
+ * getWindows gets all windows and their tabs, and stores them for future use.
+ *
+ * @param {(windows: chrome.windows.Window[]) => void} callback
+ * @returns {void}
+ */
+function getWindows(callback: (windows: chrome.windows.Window[]) => void): void {
+	chrome.windows.getAll({populate: true}, (windows : chrome.windows.Window[]) => {
+		windowCache = windows;
+		callback(windows);
+	});
 }