1 files changed, 75 insertions, 0 deletions
diff --git a/browser/components/sessionstore/test/browser_send_async_message_oom.js b/browser/components/sessionstore/test/browser_send_async_message_oom.js
new file mode 100644
index 0000000000..7e807f2fbd
--- /dev/null
+++ b/browser/components/sessionstore/test/browser_send_async_message_oom.js
@@ -0,0 +1,75 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+
+const HISTOGRAM_NAME = "FX_SESSION_RESTORE_SEND_UPDATE_CAUSED_OOM";
+
+/**
+ * Test that an OOM in sendAsyncMessage in a framescript will be reported
+ * to Telemetry.
+ */
+
+add_setup(async function () {
+  Services.telemetry.canRecordExtended = true;
+});
+
+function frameScript() {
+  // Make send[A]syncMessage("SessionStore:update", ...) simulate OOM.
+  // Other operations are unaffected.
+  let mm = docShell.messageManager;
+
+  let wrap = function (original) {
+    return function (name, ...args) {
+      if (name != "SessionStore:update") {
+        return original(name, ...args);
+      }
+      throw new Components.Exception(
+        "Simulated OOM",
+        Cr.NS_ERROR_OUT_OF_MEMORY
+      );
+    };
+  };
+
+  mm.sendAsyncMessage = wrap(mm.sendAsyncMessage.bind(mm));
+  mm.sendSyncMessage = wrap(mm.sendSyncMessage.bind(mm));
+}
+
+add_task(async function () {
+  // Capture original state.
+  let snapshot = Services.telemetry.getHistogramById(HISTOGRAM_NAME).snapshot();
+
+  // Open a browser, configure it to cause OOM.
+  let newTab = BrowserTestUtils.addTab(gBrowser, "about:robots");
+  let browser = newTab.linkedBrowser;
+  await ContentTask.spawn(browser, null, frameScript);
+
+  let promiseReported = new Promise(resolve => {
+    browser.messageManager.addMessageListener("SessionStore:error", resolve);
+  });
+
+  // Attempt to flush. This should fail.
+  let promiseFlushed = TabStateFlusher.flush(browser);
+  promiseFlushed.then(success => {
+    if (success) {
+      throw new Error("Flush should have failed");
+    }
+  });
+
+  // The frame script should report an error.
+  await promiseReported;
+
+  // Give us some time to handle that error.
+  await new Promise(resolve => setTimeout(resolve, 10));
+
+  // By now, Telemetry should have been updated.
+  let snapshot2 = Services.telemetry
+    .getHistogramById(HISTOGRAM_NAME)
+    .snapshot();
+  gBrowser.removeTab(newTab);
+
+  Assert.ok(snapshot2.sum > snapshot.sum);
+});
+
+add_task(async function cleanup() {
+  Services.telemetry.canRecordExtended = false;
+});