Bug 1249845 - Store the e10s rollout cohort in the telemetry environment. r=gfritzsche

toolkit/components/telemetry/TelemetryEnvironment.jsm

@@ -176,6 +176,7 @@ const PREF_PARTNER_ID = "mozilla.partner.id";
 const PREF_UPDATE_ENABLED = "app.update.enabled";
 const PREF_UPDATE_AUTODOWNLOAD = "app.update.auto";
 const PREF_SEARCH_COHORT = "browser.search.cohort";
+const PREF_E10S_COHORT = "e10s.rollout.cohort";
 
 const EXPERIMENTS_CHANGED_TOPIC = "experiments-changed";
 const SEARCH_ENGINE_MODIFIED_TOPIC = "browser-search-engine-modified";
@@ -1110,6 +1111,7 @@ EnvironmentCache.prototype = {
     this._currentEnvironment.settings = {
       blocklistEnabled: Preferences.get(PREF_BLOCKLIST_ENABLED, true),
       e10sEnabled: Services.appinfo.browserTabsRemoteAutostart,
+      e10sCohort: Preferences.get(PREF_E10S_COHORT, "unknown"),
       telemetryEnabled: Utils.isTelemetryEnabled,
       locale: getBrowserLocale(),
       update: {

toolkit/components/telemetry/docs/environment.rst

@@ -43,6 +43,7 @@ Structure::
         },
         searchCohort: <string>, // optional, contains an identifier for any active search A/B experiments
         e10sEnabled: <bool>, // whether e10s is on, i.e. browser tabs open by default in a different process
+        e10sCohort: <string>, // which e10s cohort was assigned for this user
         telemetryEnabled: <bool>, // false on failure
         locale: <string>, // e.g. "it", null on failure
         update: {

toolkit/components/telemetry/tests/unit/test_TelemetryEnvironment.js

@@ -341,6 +341,7 @@ function checkSettingsSection(data) {
   const EXPECTED_FIELDS_TYPES = {
     blocklistEnabled: "boolean",
     e10sEnabled: "boolean",
+    e10sCohort: "string",
     telemetryEnabled: "boolean",
     locale: "string",
     update: "object",