Backed out changeset a7a3ec0f3d35 (bug 1908019) for causing multiple failures.

browser/app/profile/firefox.js

@@ -1991,10 +1991,6 @@ pref("sidebar.animation.duration-ms", 200);
 pref("sidebar.main.tools", "aichat,syncedtabs,history");
 pref("sidebar.verticalTabs", false);
 pref("sidebar.visibility", "always-show");
-// Sidebar UI state is stored per-window via session restore. Use this pref
-// as a backup to restore the sidebar UI state when a user has PPB mode on
-// or has history cleared on browser close.
-pref("sidebar.backupState", "{}");
 
 pref("browser.ml.chat.enabled", false);
 pref("browser.ml.chat.hideLocalhost", true);

browser/components/sessionstore/SessionStore.sys.mjs

@@ -4557,7 +4557,24 @@ var SessionStoreInternal = {
       delete winData.hidden;
     }
 
-    winData.sidebar = aWindow.SidebarController.getUIState();
+    let sidebarBox = aWindow.document.getElementById("sidebar-box");
+    let command = sidebarBox.getAttribute("sidebarcommand");
+    winData.sidebar = {};
+    if (sidebarBox.style.width) {
+      winData.sidebar.width = sidebarBox.style.width;
+    }
+    if (command && sidebarBox.getAttribute("checked") == "true") {
+      winData.sidebar.command = command;
+    } else if (winData.sidebar?.command) {
+      delete winData.sidebar.command;
+    }
+
+    if (aWindow.SidebarController.revampComponentsLoaded) {
+      winData.sidebar = Object.assign(winData.sidebar || {}, {
+        expanded: aWindow.SidebarController.sidebarMain.expanded,
+        hidden: aWindow.SidebarController.sidebarContainer.hidden,
+      });
+    }
 
     let workspaceID = aWindow.getWorkspaceID();
     if (workspaceID) {
@@ -5615,8 +5632,30 @@ var SessionStoreInternal = {
    *        Object containing command (sidebarcommand/category) and styles
    */
   restoreSidebar(aWindow, aSidebar, isPopup) {
+    if (!aSidebar) {
+      return;
+    }
     if (!isPopup) {
-      aWindow.SidebarController.setUIState(aSidebar);
+      let sidebarBox = aWindow.document.getElementById("sidebar-box");
+      // Always restore sidebar width
+      if (aSidebar.width) {
+        sidebarBox.style.width = aSidebar.width;
+      }
+      if (
+        aSidebar.command &&
+        (sidebarBox.getAttribute("sidebarcommand") != aSidebar.command ||
+          !sidebarBox.getAttribute("checked"))
+      ) {
+        aWindow.SidebarController.showInitially(aSidebar.command);
+      }
+    }
+    if (aWindow.SidebarController.sidebarRevampEnabled) {
+      const { SidebarController } = aWindow;
+      SidebarController.promiseInitialized.then(() => {
+        SidebarController.toggleExpanded(aSidebar.expanded);
+        SidebarController.sidebarContainer.hidden = aSidebar.hidden;
+        SidebarController.updateToolbarButton();
+      });
     }
   },
 

browser/components/sessionstore/test/marionette/test_restore_sidebar.py

@@ -246,44 +246,3 @@ class TestSessionRestore(SessionStoreTestCase):
             ),
             "Sidebar visibility state has been restored.",
         )
-
-    def test_restore_sidebar_open_from_backup_pref(self):
-        self.marionette.execute_script(
-            """
-            Services.prefs.setBoolPref("sidebar.revamp", true);
-            Services.prefs.setBoolPref("browser.privatebrowsing.autostart", true);
-            """
-        )
-        self.marionette.restart()
-        self.marionette.set_context("chrome")
-
-        # Open the history panel.
-        self.marionette.execute_async_script(
-            """
-            let resolve = arguments[0];
-            let window = BrowserWindowTracker.getTopWindow();
-            window.SidebarController.show("viewHistorySidebar").then(resolve);
-            """
-        )
-
-        # Restart the browser.
-        self.marionette.restart()
-        self.marionette.execute_async_script(
-            """
-            let resolve = arguments[0];
-            let { BrowserInitState } = ChromeUtils.importESModule("resource:///modules/BrowserGlue.sys.mjs");
-            BrowserInitState.startupIdleTaskPromise.then(resolve);
-            """
-        )
-
-        # Check to see if the history panel was restored.
-        self.assertEqual(
-            self.marionette.execute_script(
-                """
-                let window = BrowserWindowTracker.getTopWindow();
-                return window.SidebarController.currentID;
-                """
-            ),
-            "viewHistorySidebar",
-            "Correct sidebar category has been restored.",
-        )

browser/components/sidebar/SidebarManager.sys.mjs

@@ -5,8 +5,6 @@
 import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
-const BACKUP_STATE_PREF = "sidebar.backupState";
-
 const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   ExperimentAPI: "resource://nimbus/ExperimentAPI.sys.mjs",
@@ -14,11 +12,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
   PrefUtils: "resource://normandy/lib/PrefUtils.sys.mjs",
 });
 XPCOMUtils.defineLazyPreferenceGetter(lazy, "sidebarNimbus", "sidebar.nimbus");
-XPCOMUtils.defineLazyPreferenceGetter(
-  lazy,
-  "sidebarBackupState",
-  BACKUP_STATE_PREF
-);
 
 export const SidebarManager = {
   /**
@@ -67,35 +60,6 @@ export const SidebarManager = {
       );
     });
   },
-
-  /**
-   * Provide a system-level "backup" state to be stored for those using "Never
-   * remember history" or "Clear history when browser closes".
-   *
-   * If it doesn't exist or isn't parsable, return `null`.
-   *
-   * @returns {object}
-   */
-  getBackupState() {
-    try {
-      return JSON.parse(lazy.sidebarBackupState);
-    } catch (e) {
-      Services.prefs.clearUserPref(BACKUP_STATE_PREF);
-      return null;
-    }
-  },
-
-  /**
-   * Set the backup state.
-   *
-   * @param {object} state
-   */
-  setBackupState(state) {
-    if (!state) {
-      return;
-    }
-    Services.prefs.setStringPref(BACKUP_STATE_PREF, JSON.stringify(state));
-  },
 };
 
 // Initialize on first import

browser/components/sidebar/browser-sidebar.js

@@ -408,14 +408,6 @@ var SidebarController = {
       this._tabstripOrientationObserverAdded = true;
     }
 
-    requestIdleCallback(() => {
-      if (!this._uiState) {
-        // UI state has not been set by SessionStore. Use backup state for now.
-        const backupState = this.SidebarManager.getBackupState();
-        this.setUIState(backupState);
-      }
-    });
-
     this._initDeferred.resolve();
   },
 
@@ -428,10 +420,8 @@ var SidebarController = {
     let enumerator = Services.wm.getEnumerator("navigator:browser");
     if (!enumerator.hasMoreElements()) {
       let xulStore = Services.xulStore;
-      xulStore.persist(this._title, "value");
 
-      const currentState = this.getUIState();
+      xulStore.persist(this._title, "value");
-      this.SidebarManager.setBackupState(currentState);
     }
 
     Services.obs.removeObserver(this, "intl:app-locales-changed");
@@ -456,50 +446,6 @@ var SidebarController = {
     this.browser.removeEventListener("resize", this._browserResizeObserver);
   },
 
-  getUIState() {
-    const state = { width: this._box.style.width, command: this.currentID };
-    if (this.sidebarRevampEnabled) {
-      state.expanded = this.sidebarMain.expanded;
-      state.hidden = this.sidebarContainer.hidden;
-    }
-    return state;
-  },
-
-  /**
-   * Update and store the UI state of the sidebar for this window.
-   *
-   * @param {object} state
-   * @param {string} state.width
-   *   Panel width of the sidebar.
-   * @param {string} state.command
-   *   Panel ID that is currently open.
-   * @param {boolean} state.expanded
-   *   Whether the sidebar launcher is expanded. (Revamp only)
-   * @param {boolean} state.hidden
-   *   Whether the sidebar is hidden. (Revamp only)
-   */
-  async setUIState(state) {
-    if (!state) {
-      return;
-    }
-    this._uiState = state;
-    if (state.width) {
-      this._box.style.width = state.width;
-    }
-    if (state.command && this.currentID != state.command && !this.isOpen) {
-      await this.showInitially(state.command);
-    }
-    if (this.sidebarRevampEnabled) {
-      // The `sidebar-main` component is lazy-loaded in the `init()` method.
-      // Wait this out to ensure that it is connected to the DOM before making
-      // any changes.
-      await this.promiseInitialized;
-      this.toggleExpanded(state.expanded);
-      this.sidebarContainer.hidden = state.hidden;
-      this.updateToolbarButton();
-    }
-  },
-
   /**
    * The handler for Services.obs.addObserver.
    */
@@ -746,8 +692,29 @@ var SidebarController = {
       this._box.setAttribute("sidebarcommand", commandID);
     }
 
-    const sourceControllerState = sourceController.getUIState();
+    // Adopt `expanded` and `hidden` states only if the opener was also using
-    this.setUIState(sourceControllerState);
+    // revamped sidebar.
+    if (this.sidebarRevampEnabled && sourceController.revampComponentsLoaded) {
+      this.promiseInitialized.then(() => {
+        this.sidebarContainer.hidden = sourceController.sidebarContainer.hidden;
+        this.toggleExpanded(sourceController.sidebarMain.expanded);
+      });
+    }
+
+    if (sourceController._box.hidden) {
+      // just hidden means we have adopted the hidden state.
+      return true;
+    }
+
+    // dynamically generated sidebars will fail this check, but we still
+    // consider it adopted.
+    if (!this.sidebars.has(commandID)) {
+      return true;
+    }
+
+    this._box.style.width = sourceController._box.style.width;
+    this.showInitially(commandID);
+
     return true;
   },