diff -r 000000000000 -r 6474c204b198 browser/components/sessionstore/test/browser_telemetry.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/sessionstore/test/browser_telemetry.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,272 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+
+let tmp = {};
+Cu.import("resource:///modules/sessionstore/SessionFile.jsm", tmp);
+let {SessionFile} = tmp;
+
+// Shortcuts for histogram names
+let Keys = {};
+for (let k of ["HISTORY", "FORMDATA", "OPEN_WINDOWS", "CLOSED_WINDOWS", "CLOSED_TABS_IN_OPEN_WINDOWS", "DOM_STORAGE"]) {
+  Keys[k] = "FX_SESSION_RESTORE_TOTAL_" + k + "_SIZE_BYTES";
+}
+
+function lt(a, b, message) {
+  isnot(a, undefined, message + " (sanity check)");
+  isnot(b, undefined, message + " (sanity check)");
+  ok(a < b, message + " ( " + a + " < " + b + ")");
+}
+function gt(a, b, message) {
+  isnot(a, undefined, message + " (sanity check)");
+  isnot(b, undefined, message + " (sanity check)");
+  ok(a > b, message + " ( " + a + " > " + b + ")");
+}
+
+add_task(function init() {
+  for (let i = ss.getClosedWindowCount() - 1; i >= 0; --i) {
+    ss.forgetClosedWindow(i);
+  }
+  for (let i = ss.getClosedTabCount(window) - 1; i >= 0; --i) {
+    ss.forgetClosedTab(window, i);
+  }
+});
+
+/**
+ * Test that Telemetry collection doesn't cause any error.
+ */
+add_task(function() {
+  info("Checking a little bit of consistency");
+  let statistics = yield promiseStats();
+
+  for (let k of Object.keys(statistics)) {
+    let data = statistics[k];
+    info("Data for " + k + ": " + data);
+    if (Array.isArray(data)) {
+      ok(data.every(x => x >= 0), "Data for " + k + " is >= 0");
+    } else {
+      ok(data >= 0, "Data for " + k + " is >= 0");
+    }
+  }
+});
+
+/**
+ * Test HISTORY key.
+ */
+add_task(function history() {
+  let KEY = Keys.HISTORY;
+  let tab = gBrowser.addTab("http://example.org:80/?");
+  yield promiseBrowserLoaded(tab.linkedBrowser);
+  try {
+    SyncHandlers.get(tab.linkedBrowser).flush();
+    let statistics = yield promiseStats();
+
+    info("Now changing history");
+    tab.linkedBrowser.loadURI("http://example.org:80/1");
+    yield promiseBrowserLoaded(tab.linkedBrowser);
+    SyncHandlers.get(tab.linkedBrowser).flush();
+    let statistics2 = yield promiseStats();
+
+    // We have changed history, so it must have increased
+    isnot(statistics[KEY], undefined, "Key was defined");
+    isnot(statistics2[KEY], undefined, "Key is still defined");
+    gt(statistics2[KEY], statistics[KEY], "The total size of HISTORY has increased");
+
+// Almost nothing else should
+    for (let k of ["FORMDATA", "DOM_STORAGE", "CLOSED_WINDOWS", "CLOSED_TABS_IN_OPEN_WINDOWS"]) {
+      is(statistics2[Keys[k]], statistics[Keys[k]], "The total size of " + k + " has not increased");
+    }
+  } finally {
+    if (tab) {
+      gBrowser.removeTab(tab);
+    }
+  }
+});
+
+/**
+ * Test CLOSED_TABS_IN_OPEN_WINDOWS key.
+ */
+add_task(function close_tab() {
+  let KEY = Keys.CLOSED_TABS_IN_OPEN_WINDOWS;
+  let tab = gBrowser.addTab("http://example.org:80/?close_tab");
+  yield promiseBrowserLoaded(tab.linkedBrowser);
+  try {
+    SyncHandlers.get(tab.linkedBrowser).flush();
+    let statistics = yield promiseStats();
+
+    info("Now closing a tab");
+    gBrowser.removeTab(tab);
+    tab = null;
+    let statistics2 = yield promiseStats();
+
+    isnot(statistics[KEY], undefined, "Key was defined");
+    isnot(statistics2[KEY], undefined, "Key is still defined");
+    gt(statistics2[KEY], statistics[KEY], "The total size of CLOSED_TABS_IN_OPEN_WINDOWS has increased");
+
+    // Almost nothing else should change
+    for (let k of ["FORMDATA", "DOM_STORAGE", "CLOSED_WINDOWS"]) {
+      is(statistics2[Keys[k]], statistics[Keys[k]], "The total size of " + k + " has not increased");
+    }
+
+  } finally {
+    if (tab) {
+      gBrowser.removeTab(tab);
+    }
+  }
+});
+
+/**
+ * Test OPEN_WINDOWS key.
+ */
+add_task(function open_window() {
+  let KEY = Keys.OPEN_WINDOWS;
+  let win;
+  try {
+    let statistics = yield promiseStats();
+    win = yield promiseNewWindowLoaded("http://example.org:80/?open_window");
+    let statistics2 = yield promiseStats();
+
+    isnot(statistics[KEY], undefined, "Key was defined");
+    isnot(statistics2[KEY], undefined, "Key is still defined");
+    gt(statistics2[KEY], statistics[KEY], "The total size of OPEN_WINDOWS has increased");
+
+    // Almost nothing else should change
+    for (let k of ["FORMDATA", "DOM_STORAGE", "CLOSED_WINDOWS", "CLOSED_TABS_IN_OPEN_WINDOWS"]) {
+      is(statistics2[Keys[k]], statistics[Keys[k]], "The total size of " + k + " has not increased");
+    }
+
+  } finally {
+    if (win) {
+      yield promiseWindowClosed(win);
+    }
+  }
+});
+
+/**
+ * Test CLOSED_WINDOWS key.
+ */
+add_task(function close_window() {
+  let KEY = Keys.CLOSED_WINDOWS;
+  let win = yield promiseNewWindowLoaded("http://example.org:80/?close_window");
+
+  // We need to add something to the window, otherwise it won't be saved
+  let tab = win.gBrowser.addTab("http://example.org:80/?close_tab");
+  yield promiseBrowserLoaded(tab.linkedBrowser);
+  try {
+    let statistics = yield promiseStats();
+    yield promiseWindowClosed(win);
+    win = null;
+    let statistics2 = yield promiseStats();
+
+    isnot(statistics[KEY], undefined, "Key was defined");
+    isnot(statistics2[KEY], undefined, "Key is still defined");
+    gt(statistics2[KEY], statistics[KEY], "The total size of CLOSED_WINDOWS has increased");
+    lt(statistics2[Keys.OPEN_WINDOWS], statistics[Keys.OPEN_WINDOWS], "The total size of OPEN_WINDOWS has decreased");
+
+    // Almost nothing else should change
+    for (let k of ["FORMDATA", "DOM_STORAGE", "CLOSED_TABS_IN_OPEN_WINDOWS"]) {
+      is(statistics2[Keys[k]], statistics[Keys[k]], "The total size of " + k + " has not increased");
+    }
+
+  } finally {
+    if (win) {
+      yield promiseWindowClosed(win);
+    }
+  }
+});
+
+
+/**
+ * Test DOM_STORAGE key.
+ */
+add_task(function dom_storage() {
+  let KEY = Keys.DOM_STORAGE;
+  let tab = gBrowser.addTab("http://example.org:80/?dom_storage");
+  yield promiseBrowserLoaded(tab.linkedBrowser);
+  try {
+    SyncHandlers.get(tab.linkedBrowser).flush();
+    let statistics = yield promiseStats();
+
+    info("Now adding some storage");
+    yield modifySessionStorage(tab.linkedBrowser, {foo: "bar"});
+    SyncHandlers.get(tab.linkedBrowser).flush();
+
+    let statistics2 = yield promiseStats();
+
+    isnot(statistics[KEY], undefined, "Key was defined");
+    isnot(statistics2[KEY], undefined, "Key is still defined");
+    gt(statistics2[KEY], statistics[KEY], "The total size of DOM_STORAGE has increased");
+
+    // Almost nothing else should change
+    for (let k of ["CLOSED_TABS_IN_OPEN_WINDOWS", "FORMDATA", "CLOSED_WINDOWS"]) {
+      is(statistics2[Keys[k]], statistics[Keys[k]], "The total size of " + k + " has not increased");
+    }
+
+  } finally {
+    if (tab) {
+      gBrowser.removeTab(tab);
+    }
+  }
+});
+
+/**
+ * Test FORMDATA key.
+ */
+add_task(function formdata() {
+  let KEY = Keys.FORMDATA;
+  let tab = gBrowser.addTab("data:text/html;charset=utf-8,<input%20id='input'>");
+  yield promiseBrowserLoaded(tab.linkedBrowser);
+  try {
+    SyncHandlers.get(tab.linkedBrowser).flush();
+    let statistics = yield promiseStats();
+
+    info("Now changing form data");
+
+    yield setInputValue(tab.linkedBrowser, {id: "input", value: "This is some form data"});
+    SyncHandlers.get(tab.linkedBrowser).flush();
+
+    let statistics2 = yield promiseStats();
+
+    isnot(statistics[KEY], undefined, "Key was defined");
+    isnot(statistics2[KEY], undefined, "Key is still defined");
+    gt(statistics2[KEY], statistics[KEY], "The total size of FORMDATA has increased");
+
+    // Almost nothing else should
+    for (let k of ["DOM_STORAGE", "CLOSED_WINDOWS", "CLOSED_TABS_IN_OPEN_WINDOWS"]) {
+      is(statistics2[Keys[k]], statistics[Keys[k]], "The total size of " + k + " has not increased");
+    }
+  } finally {
+    if (tab) {
+      gBrowser.removeTab(tab);
+    }
+  }
+});
+
+add_task(function* test_sessionRestoreInit() {
+   let info = Cc["@mozilla.org/toolkit/app-startup;1"].
+     getService(Ci.nsIAppStartup).
+     getStartupInfo();
+  ok(info.sessionRestoreInit > info.process, "sessionRestoreInit is after process creation");
+  ok(info.sessionRestoreInit <
+    Date.now() + 10000 /* Date.now() is non-monotonic, let's play it paranoid*/,
+    "sessionRestoreInit is before now");
+});
+
+/**
+ * Get the latest statistics.
+ */
+function promiseStats() {
+  let state = ss.getBrowserState();
+  info("Stats: " + state);
+  return SessionFile.gatherTelemetry(state);
+}
+
+
+function modifySessionStorage(browser, data) {
+  browser.messageManager.sendAsyncMessage("ss-test:modifySessionStorage", data);
+  return promiseContentMessage(browser, "ss-test:MozStorageChanged");
+}
+
+function setInputValue(browser, data) {
+  return sendMessage(browser, "ss-test:setInputValue", data);
+}