Bug 1816969 - Fix runtime errors with MOZ_SERVICES_SYNC=False. r=mossop

Some checks on MOZ_SERVICES_SYNC have been removed in Bug 1227361, but
it is still used in a few places in the codebase.
Trying to set it to False results in some runtime errors, that this
commit fixes.

Differential Revision: https://phabricator.services.mozilla.com/D170047

browser/base/content/browser-sync.js

@@ -5,10 +5,6 @@
 // This file is loaded into the browser window scope.
 /* eslint-env mozilla/browser-window */
 
-const { UIState } = ChromeUtils.importESModule(
-  "resource://services-sync/UIState.sys.mjs"
-);
-
 ChromeUtils.defineModuleGetter(
   this,
   "FxAccounts",
@@ -21,6 +17,7 @@ ChromeUtils.defineModuleGetter(
 );
 ChromeUtils.defineESModuleGetters(this, {
   SyncedTabs: "resource://services-sync/SyncedTabs.sys.mjs",
+  UIState: "resource://services-sync/UIState.sys.mjs",
   Weave: "resource://services-sync/main.sys.mjs",
 });
 
@@ -337,7 +334,9 @@ var gSync = {
   // once syncing completes (bug 1239042).
   _syncStartTime: 0,
   _syncAnimationTimer: 0,
-  _obs: ["weave:engine:sync:finish", "quit-application", UIState.ON_UPDATE],
+  _obs: AppConstants.MOZ_SERVICES_SYNC
+    ? ["weave:engine:sync:finish", "quit-application", UIState.ON_UPDATE]
+    : [],
 
   get log() {
     if (!this._log) {
@@ -455,7 +454,7 @@ var gSync = {
 
     this._definePrefGetters();
 
-    if (!this.FXA_ENABLED) {
+    if (!AppConstants.MOZ_SERVICES_SYNC || !this.FXA_ENABLED) {
       this.onFxaDisabled();
       return;
     }
@@ -1567,7 +1566,7 @@ var gSync = {
 
   // "Send Page to Device" and "Send Link to Device" menu items
   updateContentContextMenu(contextMenu) {
-    if (!this.FXA_ENABLED) {
+    if (!AppConstants.MOZ_SERVICES_SYNC || !this.FXA_ENABLED) {
       // These items are hidden by default. No need to do anything.
       return false;
     }

browser/components/BrowserGlue.sys.mjs

@@ -831,11 +831,13 @@ let JSWINDOWACTORS = {
   },
 };
 
-XPCOMUtils.defineLazyGetter(
-  lazy,
-  "WeaveService",
-  () => Cc["@mozilla.org/weave/service;1"].getService().wrappedJSObject
-);
+if (AppConstants.MOZ_SERVICES_SYNC) {
+  XPCOMUtils.defineLazyGetter(
+    lazy,
+    "WeaveService",
+    () => Cc["@mozilla.org/weave/service;1"].getService().wrappedJSObject
+  );
+}
 
 if (AppConstants.MOZ_CRASHREPORTER) {
   XPCOMUtils.defineLazyModuleGetters(lazy, {
@@ -2825,7 +2827,7 @@ BrowserGlue.prototype = {
       {
         name: "WeaveService",
         task: async () => {
-          if (lazy.WeaveService.enabled) {
+          if (lazy.WeaveService?.enabled) {
             await lazy.WeaveService.whenLoaded();
             lazy.WeaveService.Weave.Service.scheduler.autoConnect();
           }

browser/installer/package-manifest.in

@@ -177,7 +177,9 @@
 @RESPATH@/components/nsUpdateService.manifest
 #endif
 @RESPATH@/components/ProcessSingleton.manifest
+#ifdef MOZ_SERVICES_SYNC
 @RESPATH@/components/SyncComponents.manifest
+#endif
 @RESPATH@/components/servicesComponents.manifest
 @RESPATH@/components/servicesSettings.manifest
 @RESPATH@/components/cryptoComponents.manifest