diff --git a/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js b/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js
index d38c96cbdfc4..79762803d8d5 100644
--- a/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js
+++ b/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js
@@ -142,6 +142,26 @@ function checkUnmodifiedForm(formNum) {
   }
 }
 
+/**
+ * @param {Function} [aFilterFn = undefined] Function to filter out irrelevant submissions.
+ * @return {Promise} resolving when a relevant form submission was processed.
+ */
+function getSubmitMessage(aFilterFn = undefined) {
+  info("getSubmitMessage");
+  return new Promise((resolve, reject) => {
+    PWMGR_COMMON_PARENT.addMessageListener("formSubmissionProcessed", function processed(...args) {
+      if (aFilterFn && !aFilterFn(...args)) {
+        // This submission isn't the one we're waiting for.
+        return;
+      }
+
+      info("got formSubmissionProcessed");
+      PWMGR_COMMON_PARENT.removeMessageListener("formSubmissionProcessed", processed);
+      resolve(...args);
+    });
+  });
+}
+
 function registerRunTests() {
   return new Promise(resolve => {
     function onDOMContentLoaded() {
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_formless_submit.html b/toolkit/components/passwordmgr/test/mochitest/test_formless_submit.html
index 9a8d01ee8c9a..b064d83a5ff0 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_formless_submit.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_formless_submit.html
@@ -129,17 +129,6 @@ const TESTCASES = [
   },
 ];
 
-function getSubmitMessage() {
-  info("getSubmitMessage");
-  return new Promise((resolve, reject) => {
-    PWMGR_COMMON_PARENT.addMessageListener("formSubmissionProcessed", function processed(...args) {
-      info("got formSubmissionProcessed");
-      PWMGR_COMMON_PARENT.removeMessageListener("formSubmissionProcessed", processed);
-      resolve(...args);
-    });
-  });
-}
-
 add_task(async function test() {
   let count = 0;
   let loginFrame = document.getElementById("loginFrame");
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_formless_submit_navigation.html b/toolkit/components/passwordmgr/test/mochitest/test_formless_submit_navigation.html
index 63f282835f26..b838b1eddf1e 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_formless_submit_navigation.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_formless_submit_navigation.html
@@ -138,26 +138,6 @@ const TESTCASES = [
   },
 ];
 
-/**
- * @param {Function} [aFilterFn = undefined] Function to filter out irrelevant submissions.
- * @return {Promise} resolving when a relevant form submission was processed.
- */
-function getSubmitMessage(aFilterFn = undefined) {
-  info("getSubmitMessage");
-  return new Promise((resolve, reject) => {
-    PWMGR_COMMON_PARENT.addMessageListener("formSubmissionProcessed", function processed(...args) {
-      if (aFilterFn && !aFilterFn(...args)) {
-        // This submission isn't the one we're waiting for.
-        return;
-      }
-
-      info("got formSubmissionProcessed");
-      PWMGR_COMMON_PARENT.removeMessageListener("formSubmissionProcessed", processed);
-      resolve(...args);
-    });
-  });
-}
-
 function filterFormSubmissions(data) {
   return data.newPasswordField.value != "ignore-form-submission";
 }
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_munged_username.html b/toolkit/components/passwordmgr/test/mochitest/test_munged_username.html
index 4c18a4ed6991..3fe42dfa8143 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_munged_username.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_munged_username.html
@@ -129,20 +129,6 @@ const TESTCASES = [
   },
 ];
 
-/**
- * @return {Promise} resolving when form submission was processed.
- */
-function getSubmitMessage() {
-  info("getSubmitMessage");
-  return new Promise((resolve, reject) => {
-    PWMGR_COMMON_PARENT.addMessageListener("formSubmissionProcessed", function processed(...args) {
-      info("got formSubmissionProcessed");
-      PWMGR_COMMON_PARENT.removeMessageListener("formSubmissionProcessed", processed);
-      resolve(...args);
-    });
-  });
-}
-
 add_task(async function test_new_logins() {
   for (let tc of TESTCASES) {
     info("Starting testcase: " + JSON.stringify(tc));
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_one_doorhanger_per_un_pw.html b/toolkit/components/passwordmgr/test/mochitest/test_one_doorhanger_per_un_pw.html
index 6ffa5110b7cd..fdd6d3a6adff 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_one_doorhanger_per_un_pw.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_one_doorhanger_per_un_pw.html
@@ -12,17 +12,6 @@
 <script>
   let chromeScript = runChecksAfterCommonInit();
 
-  function getSubmitMessage() {
-    info("getSubmitMessage");
-    return new Promise((resolve, reject) => {
-      chromeScript.addMessageListener("formSubmissionProcessed", function processed(...args) {
-        info("got formSubmissionProcessed");
-        chromeScript.removeMessageListener("formSubmissionProcessed", processed);
-        resolve(...args);
-      });
-    });
-  }
-
   SimpleTest.requestFlakyTimeout("Giving a chance for the unexpected popupshown to occur");
 </script>
 <p id="display"></p>
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_onsubmit_value_change.html b/toolkit/components/passwordmgr/test/mochitest/test_onsubmit_value_change.html
index 1904366e62e0..3d52e330bd19 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_onsubmit_value_change.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_onsubmit_value_change.html
@@ -12,17 +12,6 @@ Login Manager test: input value change right after onsubmit event
 
 <script>
   let chromeScript = runChecksAfterCommonInit();
-
-  function getSubmitMessage() {
-    info("getSubmitMessage");
-    return new Promise((resolve, reject) => {
-      chromeScript.addMessageListener("formSubmissionProcessed", function processed(...args) {
-        info("got formSubmissionProcessed");
-        chromeScript.removeMessageListener("formSubmissionProcessed", processed);
-        resolve(...args);
-      });
-    });
-  }
 </script>
 <p id="display"></p>
 
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_password_length.html b/toolkit/components/passwordmgr/test/mochitest/test_password_length.html
index 90a82e3b1074..9a92a85bd865 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_password_length.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_password_length.html
@@ -77,19 +77,6 @@ const TESTCASES = [
   },
 ];
 
-/**
- * @return {Promise} resolving when form submission was processed.
- */
-function getSubmitMessage() {
-  return new Promise((resolve, reject) => {
-    PWMGR_COMMON_PARENT.addMessageListener("formSubmissionProcessed", function processed(...args) {
-      info("got formSubmissionProcessed");
-      PWMGR_COMMON_PARENT.removeMessageListener("formSubmissionProcessed", processed);
-      resolve(...args);
-    });
-  });
-}
-
 add_task(async function test_password_lengths() {
   for (let tc of TESTCASES) {
     info("Starting testcase: " + tc.testName + ", " + JSON.stringify([tc.pword1, tc.pword2]));