3 files changed, 123 insertions, 0 deletions
diff --git a/comm/mail/components/prompts/PromptCollection.jsm b/comm/mail/components/prompts/PromptCollection.jsm
new file mode 100644
index 0000000000..ddb413de6f
--- /dev/null
+++ b/comm/mail/components/prompts/PromptCollection.jsm
@@ -0,0 +1,100 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["PromptCollection"];
+
+const { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+
+/**
+ * Implements nsIPromptCollection
+ *
+ * @class PromptCollection
+ */
+class PromptCollection {
+  asyncBeforeUnloadCheck(browsingContext) {
+    let title;
+    let message;
+    let leaveLabel;
+    let stayLabel;
+
+    try {
+      title = this.domBundle.GetStringFromName("OnBeforeUnloadTitle");
+      message = this.domBundle.GetStringFromName("OnBeforeUnloadMessage2");
+      leaveLabel = this.domBundle.GetStringFromName(
+        "OnBeforeUnloadLeaveButton"
+      );
+      stayLabel = this.domBundle.GetStringFromName("OnBeforeUnloadStayButton");
+    } catch (exception) {
+      console.error("Failed to get strings from dom.properties");
+      return false;
+    }
+
+    let contentViewer = browsingContext?.docShell?.contentViewer;
+
+    // TODO: Do we really want to allow modal dialogs from inactive
+    // content viewers at all, particularly for permit unload prompts?
+    let modalAllowed = contentViewer
+      ? contentViewer.isTabModalPromptAllowed
+      : browsingContext.ancestorsAreCurrent;
+
+    let modalType =
+      Ci.nsIPromptService[
+        modalAllowed ? "MODAL_TYPE_CONTENT" : "MODAL_TYPE_WINDOW"
+      ];
+
+    let buttonFlags =
+      Ci.nsIPromptService.BUTTON_POS_0_DEFAULT |
+      (Ci.nsIPromptService.BUTTON_TITLE_IS_STRING *
+        Ci.nsIPromptService.BUTTON_POS_0) |
+      (Ci.nsIPromptService.BUTTON_TITLE_IS_STRING *
+        Ci.nsIPromptService.BUTTON_POS_1);
+
+    return Services.prompt
+      .asyncConfirmEx(
+        browsingContext,
+        modalType,
+        title,
+        message,
+        buttonFlags,
+        leaveLabel,
+        stayLabel,
+        null,
+        null,
+        false,
+        // Tell the prompt service that this is a permit unload prompt
+        // so that it can set the appropriate flag on the detail object
+        // of the events it dispatches.
+        { inPermitUnload: true }
+      )
+      .then(
+        result =>
+          result.QueryInterface(Ci.nsIPropertyBag2).get("buttonNumClicked") == 0
+      );
+  }
+}
+
+XPCOMUtils.defineLazyGetter(
+  PromptCollection.prototype,
+  "domBundle",
+  function () {
+    let bundle = Services.strings.createBundle(
+      "chrome://global/locale/dom/dom.properties"
+    );
+    if (!bundle) {
+      throw new Error("String bundle for dom not present!");
+    }
+    return bundle;
+  }
+);
+
+PromptCollection.prototype.classID = Components.ID(
+  "{7913837c-9623-11ea-bb37-0242ac130002}"
+);
+PromptCollection.prototype.QueryInterface = ChromeUtils.generateQI([
+  "nsIPromptCollection",
+]);
diff --git a/comm/mail/components/prompts/components.conf b/comm/mail/components/prompts/components.conf
new file mode 100644
index 0000000000..0c00e72d67
--- /dev/null
+++ b/comm/mail/components/prompts/components.conf
@@ -0,0 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+Classes = [
+    {
+        'cid': '{7913837c-9623-11ea-bb37-0242ac130002}',
+        'contract_ids': ['@mozilla.org/embedcomp/prompt-collection;1'],
+        'jsm': 'resource:///modules/PromptCollection.jsm',
+        'constructor': 'PromptCollection',
+    },
+]
diff --git a/comm/mail/components/prompts/moz.build b/comm/mail/components/prompts/moz.build
new file mode 100644
index 0000000000..143c3dcd8d
--- /dev/null
+++ b/comm/mail/components/prompts/moz.build
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+EXTRA_JS_MODULES += [
+    "PromptCollection.jsm",
+]
+
+XPCOM_MANIFESTS += [
+    "components.conf",
+]