--- a/netwerk/cookie/nsCookieService.cpp
+++ b/netwerk/cookie/nsCookieService.cpp
@@ -2489,16 +2489,19 @@ nsCookieService::AddNative(const nsACStr
     return NS_ERROR_FAILURE;
   }
 
   if (!mDBState) {
     NS_WARNING("No DBState! Profile already closed?");
     return NS_ERROR_NOT_AVAILABLE;
   }
 
+  AutoRestore<DBState*> savePrevDBState(mDBState);
+  mDBState = (aOriginAttributes->mPrivateBrowsingId > 0) ? mPrivateDBState : mDefaultDBState;
+
   // first, normalize the hostname, and fail if it contains illegal characters.
   nsAutoCString host(aHost);
   nsresult rv = NormalizeHost(host);
   NS_ENSURE_SUCCESS(rv, rv);
 
   // get the base domain for the host URI.
   // e.g. for "www.bbc.co.uk", this would be "bbc.co.uk".
   nsAutoCString baseDomain;
@@ -2531,16 +2534,19 @@ nsCookieService::Remove(const nsACString
                         const nsACString& aName, const nsACString& aPath,
                         bool aBlocked)
 {
   if (!mDBState) {
     NS_WARNING("No DBState! Profile already closed?");
     return NS_ERROR_NOT_AVAILABLE;
   }
 
+  AutoRestore<DBState*> savePrevDBState(mDBState);
+  mDBState = (aAttrs.mPrivateBrowsingId > 0) ? mPrivateDBState : mDefaultDBState;
+
   // first, normalize the hostname, and fail if it contains illegal characters.
   nsAutoCString host(aHost);
   nsresult rv = NormalizeHost(host);
   NS_ENSURE_SUCCESS(rv, rv);
 
   nsAutoCString baseDomain;
   rv = GetBaseDomainFromHost(host, baseDomain);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -2616,35 +2622,16 @@ nsCookieService::RemoveNative(const nsAC
   nsresult rv = Remove(aHost, *aOriginAttributes, aName, aPath, aBlocked);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;
   }
 
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsCookieService::UsePrivateMode(bool aIsPrivate,
-                                nsIPrivateModeCallback* aCallback)
-{
-  if (!aCallback) {
-    return NS_ERROR_INVALID_ARG;
-  }
-
-  if (!mDBState) {
-    NS_WARNING("No DBState! Profile already closed?");
-    return NS_ERROR_NOT_AVAILABLE;
-  }
-
-  AutoRestore<DBState*> savePrevDBState(mDBState);
-  mDBState = aIsPrivate ? mPrivateDBState : mDefaultDBState;
-
-  return aCallback->Callback();
-}
-
 /******************************************************************************
  * nsCookieService impl:
  * private file I/O functions
  ******************************************************************************/
 
 // Begin an asynchronous read from the database.
 OpenDBResult
 nsCookieService::Read()
@@ -4636,16 +4623,19 @@ nsCookieService::CookieExistsNative(nsIC
   NS_ENSURE_ARG_POINTER(aOriginAttributes);
   NS_ENSURE_ARG_POINTER(aFoundCookie);
 
   if (!mDBState) {
     NS_WARNING("No DBState! Profile already closed?");
     return NS_ERROR_NOT_AVAILABLE;
   }
 
+  AutoRestore<DBState*> savePrevDBState(mDBState);
+  mDBState = (aOriginAttributes->mPrivateBrowsingId > 0) ? mPrivateDBState : mDefaultDBState;
+
   nsAutoCString host, name, path;
   nsresult rv = aCookie->GetHost(host);
   NS_ENSURE_SUCCESS(rv, rv);
   rv = aCookie->GetName(name);
   NS_ENSURE_SUCCESS(rv, rv);
   rv = aCookie->GetPath(path);
   NS_ENSURE_SUCCESS(rv, rv);
 
@@ -4826,16 +4816,19 @@ nsCookieService::GetCookiesFromHost(cons
   rv = InitializeOriginAttributes(&attrs,
                                   aOriginAttributes,
                                   aCx,
                                   aArgc,
                                   u"nsICookieManager2.getCookiesFromHost()",
                                   u"2");
   NS_ENSURE_SUCCESS(rv, rv);
 
+  AutoRestore<DBState*> savePrevDBState(mDBState);
+  mDBState = (attrs.mPrivateBrowsingId > 0) ? mPrivateDBState : mDefaultDBState;
+
   nsCookieKey key = nsCookieKey(baseDomain, attrs);
   EnsureReadDomain(key);
 
   nsCookieEntry *entry = mDBState->hostTable.GetEntry(key);
   if (!entry)
     return NS_NewEmptyEnumerator(aEnumerator);
 
   nsCOMArray<nsICookie> cookieList(mMaxCookiesPerHost);
@@ -4874,16 +4867,20 @@ nsCookieService::GetCookiesWithOriginAtt
     const nsCString& aBaseDomain,
     nsISimpleEnumerator **aEnumerator)
 {
   if (!mDBState) {
     NS_WARNING("No DBState! Profile already closed?");
     return NS_ERROR_NOT_AVAILABLE;
   }
 
+  AutoRestore<DBState*> savePrevDBState(mDBState);
+  mDBState = (aPattern.mPrivateBrowsingId.WasPassed() &&
+      aPattern.mPrivateBrowsingId.Value() > 0) ? mPrivateDBState : mDefaultDBState;
+
   nsCOMArray<nsICookie> cookies;
   for (auto iter = mDBState->hostTable.Iter(); !iter.Done(); iter.Next()) {
     nsCookieEntry* entry = iter.Get();
 
     if (!aBaseDomain.IsEmpty() && !aBaseDomain.Equals(entry->mBaseDomain)) {
       continue;
     }
 
@@ -4928,16 +4925,20 @@ nsCookieService::RemoveCookiesWithOrigin
     const mozilla::OriginAttributesPattern& aPattern,
     const nsCString& aBaseDomain)
 {
   if (!mDBState) {
     NS_WARNING("No DBState! Profile already close?");
     return NS_ERROR_NOT_AVAILABLE;
   }
 
+  AutoRestore<DBState*> savePrevDBState(mDBState);
+  mDBState = (aPattern.mPrivateBrowsingId.WasPassed() &&
+      aPattern.mPrivateBrowsingId.Value() > 0) ? mPrivateDBState : mDefaultDBState;
+
   mozStorageTransaction transaction(mDBState->dbConn, false);
   // Iterate the hash table of nsCookieEntry.
   for (auto iter = mDBState->hostTable.Iter(); !iter.Done(); iter.Next()) {
     nsCookieEntry* entry = iter.Get();
 
     if (!aBaseDomain.IsEmpty() && !aBaseDomain.Equals(entry->mBaseDomain)) {
       continue;
     }

--- a/netwerk/cookie/nsICookieManager.idl
+++ b/netwerk/cookie/nsICookieManager.idl
@@ -33,22 +33,26 @@ interface nsICookieManager : nsISupports
   /**
    * Called to remove all cookies from the cookie list
    */
   void removeAll();
 
   /**
    * Called to enumerate through each cookie in the cookie list.
    * The objects enumerated over are of type nsICookie
+   * This enumerator should only be used for non-private browsing cookies.
+   * To retrieve an enumerator for private browsing cookies, use
+   * getCookiesWithOriginAttributes from nsICookieManager2.
    */
   readonly attribute nsISimpleEnumerator enumerator;
 
   /**
    * Called to enumerate through each session cookie in the cookie list.
    * The objects enumerated over are of type nsICookie
+   * This enumerator should only be used for non-private browsing cookies.
    */
   readonly attribute nsISimpleEnumerator sessionEnumerator;
 
   /**
    * Called to remove an individual cookie from the cookie list, specified
    * by host, name, and path. If the cookie cannot be found, no exception
    * is thrown. Typically, the arguments to this method will be obtained
    * directly from the desired nsICookie object.
@@ -74,21 +78,9 @@ interface nsICookieManager : nsISupports
               [optional] in jsval aOriginAttributes);
 
   [notxpcom]
   nsresult removeNative(in AUTF8String   aHost,
                         in ACString      aName,
                         in AUTF8String   aPath,
                         in boolean       aBlocked,
                         in OriginAttributesPtr aOriginAttributes);
-
-  /**
-   * Set the cookie manager to work on private or non-private cookies for the
-   * duration of the callback.
-   *
-   * @param aIsPrivate True to work on private cookies, false to work on
-   *                   non-private cookies.
-   * @param aCallback Methods on the cookie manager interface will work on
-   *                  private or non-private cookies for the duration of this
-   *                  callback.
-   */
-  void usePrivateMode(in boolean aIsPrivate, in nsIPrivateModeCallback aCallback);
 };

--- a/toolkit/components/extensions/ext-cookies.js
+++ b/toolkit/components/extensions/ext-cookies.js
@@ -170,34 +170,32 @@ function* query(detailsIn, props, contex
     storeId = PRIVATE_STORE;
   } else if ("storeId" in details) {
     storeId = details.storeId;
   }
 
   // We can use getCookiesFromHost for faster searching.
   let enumerator;
   let uri;
+  let originAttributes = {
+    userContextId,
+    privateBrowsingId: isPrivate ? 1 : 0,
+  };
   if ("url" in details) {
     try {
       uri = NetUtil.newURI(details.url).QueryInterface(Ci.nsIURL);
-      Services.cookies.usePrivateMode(isPrivate, () => {
-        enumerator = Services.cookies.getCookiesFromHost(uri.host, {userContextId});
-      });
+      enumerator = Services.cookies.getCookiesFromHost(uri.host, originAttributes);
     } catch (ex) {
       // This often happens for about: URLs
       return;
     }
   } else if ("domain" in details) {
-    Services.cookies.usePrivateMode(isPrivate, () => {
-      enumerator = Services.cookies.getCookiesFromHost(details.domain, {userContextId});
-    });
+    enumerator = Services.cookies.getCookiesFromHost(details.domain, originAttributes);
   } else {
-    Services.cookies.usePrivateMode(isPrivate, () => {
-      enumerator = Services.cookies.enumerator;
-    });
+    enumerator = Services.cookies.getCookiesWithOriginAttributes(JSON.stringify(originAttributes));
   }
 
   // Based on nsCookieService::GetCookieStringInternal
   function matches(cookie) {
     function domainMatches(host) {
       return cookie.rawHost == host || (cookie.isDomain && host.endsWith(cookie.host));
     }
 
@@ -233,20 +231,16 @@ function* query(detailsIn, props, contex
         return false;
       }
     }
 
     if ("name" in details && details.name != cookie.name) {
       return false;
     }
 
-    if (userContextId != cookie.originAttributes.userContextId) {
-      return false;
-    }
-
     // "Restricts the retrieved cookies to those whose domains match or are subdomains of this one."
     if ("domain" in details && !isSubdomain(cookie.rawHost, details.domain)) {
       return false;
     }
 
     // "Restricts the retrieved cookies to those whose path exactly matches this string.""
     if ("path" in details && details.path != cookie.path) {
       return false;
@@ -335,31 +329,32 @@ this.cookies = class extends ExtensionAP
             return Promise.reject({message: "Unknown storeId"});
           }
 
           let cookieAttrs = {host: details.domain, path: path, isSecure: secure};
           if (!checkSetCookiePermissions(extension, uri, cookieAttrs)) {
             return Promise.reject({message: `Permission denied to set cookie ${JSON.stringify(details)}`});
           }
 
+          let originAttributes = {
+            userContextId,
+            privateBrowsingId: isPrivate ? 1 : 0,
+          };
+
           // The permission check may have modified the domain, so use
           // the new value instead.
-          Services.cookies.usePrivateMode(isPrivate, () => {
-            Services.cookies.add(cookieAttrs.host, path, name, value,
-                                 secure, httpOnly, isSession, expiry, {userContextId});
-          });
+          Services.cookies.add(cookieAttrs.host, path, name, value,
+                               secure, httpOnly, isSession, expiry, originAttributes);
 
           return self.cookies.get(details);
         },
 
         remove: function(details) {
-          for (let {cookie, isPrivate, storeId} of query(details, ["url", "name", "storeId"], context)) {
-            Services.cookies.usePrivateMode(isPrivate, () => {
-              Services.cookies.remove(cookie.host, cookie.name, cookie.path, false, cookie.originAttributes);
-            });
+          for (let {cookie, storeId} of query(details, ["url", "name", "storeId"], context)) {
+            Services.cookies.remove(cookie.host, cookie.name, cookie.path, false, cookie.originAttributes);
 
             // Todo: could there be multiple per subdomain?
             return Promise.resolve({
               url: details.url,
               name: details.name,
               storeId,
             });
           }