Bug 1878636 - remove filterPrivateTabs as it creates needless performance churn, r=sfoster,sessionstore-reviewers,kaya,farre

Differential Revision: https://phabricator.services.mozilla.com/D200687

Author: gijsk

browser/components/sessionstore/SessionStore.sys.mjs

@@ -222,7 +222,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
   DevToolsShim: "chrome://devtools-startup/content/DevToolsShim.sys.mjs",
   E10SUtils: "resource://gre/modules/E10SUtils.sys.mjs",
   HomePage: "resource:///modules/HomePage.sys.mjs",
-  PrivacyFilter: "resource://gre/modules/sessionstore/PrivacyFilter.sys.mjs",
   RunState: "resource:///modules/sessionstore/RunState.sys.mjs",
   SessionCookies: "resource:///modules/sessionstore/SessionCookies.sys.mjs",
   SessionFile: "resource:///modules/sessionstore/SessionFile.sys.mjs",
@@ -2320,8 +2319,6 @@ var SessionStoreInternal = {
       // 3) When the flush is complete, revisit our decision to store the window
       //    in _closedWindows, and add/remove as necessary.
       if (!winData.isPrivate) {
-        // Remove any open private tabs the window may contain.
-        lazy.PrivacyFilter.filterPrivateTabs(winData);
         this.maybeSaveClosedWindow(winData, isLastWindow);
       }
 
@@ -2343,9 +2340,6 @@ var SessionStoreInternal = {
         // Save non-private windows if they have at
         // least one saveable tab or are the last window.
         if (!winData.isPrivate) {
-          // It's possible that a tab switched its privacy state at some point
-          // before our flush, so we need to filter again.
-          lazy.PrivacyFilter.filterPrivateTabs(winData);
           this.maybeSaveClosedWindow(winData, isLastWindow, true);
 
           if (!isLastWindow && winData.closedId > -1) {

toolkit/modules/sessionstore/PrivacyFilter.sys.mjs

@@ -103,48 +103,12 @@ export var PrivacyFilter = Object.freeze({
         if (browserState.selectedWindow >= i) {
           browserState.selectedWindow--;
         }
-      } else {
-        // Remove private tabs from all open non-private windows.
-        this.filterPrivateTabs(win);
       }
     }
 
     // Remove private closed windows.
     browserState._closedWindows = browserState._closedWindows.filter(
       win => !win.isPrivate
     );
-
-    // Remove private tabs from all remaining closed windows.
-    browserState._closedWindows.forEach(win => this.filterPrivateTabs(win));
-  },
-
-  /**
-   * Removes open private tabs from a given window state object.
-   *
-   * @param winState (object)
-   *        The window state for which we remove any private tabs.
-   *        The given object will be modified.
-   */
-  filterPrivateTabs(winState) {
-    // Remove open private tabs.
-    for (let i = winState.tabs.length - 1; i >= 0; i--) {
-      let tab = winState.tabs[i];
-
-      // Bug 1740261 - We end up with `null` entries in winState.tabs, which if
-      // we don't check for we end up throwing here. This does not fix the issue of
-      // how null tabs are getting into the state.
-      if (!tab || tab.isPrivate) {
-        winState.tabs.splice(i, 1);
-
-        if (winState.selected >= i) {
-          winState.selected--;
-        }
-      }
-    }
-
-    // Note that closed private tabs are only stored for private windows.
-    // There is no need to call this function for private windows as the
-    // whole window state should just be discarded so we explicitly don't
-    // try to remove closed private tabs as an optimization.
   },
 });