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diff --git a/third_party/rust/webext-storage/src/store.rs b/third_party/rust/webext-storage/src/store.rs
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+++ b/third_party/rust/webext-storage/src/store.rs
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::api::{self, StorageChanges};
+use crate::db::{StorageDb, ThreadSafeStorageDb};
+use crate::error::*;
+use crate::migration::{migrate, MigrationInfo};
+use crate::sync;
+use std::path::Path;
+use std::sync::Arc;
+
+use interrupt_support::SqlInterruptHandle;
+use serde_json::Value as JsonValue;
+
+/// A store is used to access `storage.sync` data. It manages an underlying
+/// database connection, and exposes methods for reading and writing storage
+/// items scoped to an extension ID. Each item is a JSON object, with one or
+/// more string keys, and values of any type that can serialize to JSON.
+///
+/// An application should create only one store, and manage the instance as a
+/// singleton. While this isn't enforced, if you make multiple stores pointing
+/// to the same database file, you are going to have a bad time: each store will
+/// create its own database connection, using up extra memory and CPU cycles,
+/// and causing write contention. For this reason, you should only call
+/// `Store::new()` (or `webext_store_new()`, from the FFI) once.
+///
+/// Note that our Db implementation is behind an Arc<> because we share that
+/// connection with our sync engines - ie, these engines also hold an Arc<>
+/// around the same object.
+pub struct Store {
+    db: Arc<ThreadSafeStorageDb>,
+}
+
+impl Store {
+    /// Creates a store backed by a database at `db_path`. The path can be a
+    /// file path or `file:` URI.
+    pub fn new(db_path: impl AsRef<Path>) -> Result<Self> {
+        let db = StorageDb::new(db_path)?;
+        Ok(Self {
+            db: Arc::new(ThreadSafeStorageDb::new(db)),
+        })
+    }
+
+    /// Creates a store backed by an in-memory database.
+    #[cfg(test)]
+    pub fn new_memory(db_path: &str) -> Result<Self> {
+        let db = StorageDb::new_memory(db_path)?;
+        Ok(Self {
+            db: Arc::new(ThreadSafeStorageDb::new(db)),
+        })
+    }
+
+    /// Returns an interrupt handle for this store.
+    pub fn interrupt_handle(&self) -> Arc<SqlInterruptHandle> {
+        self.db.interrupt_handle()
+    }
+
+    /// Sets one or more JSON key-value pairs for an extension ID. Returns a
+    /// list of changes, with existing and new values for each key in `val`.
+    pub fn set(&self, ext_id: &str, val: JsonValue) -> Result<StorageChanges> {
+        let db = self.db.lock();
+        let tx = db.unchecked_transaction()?;
+        let result = api::set(&tx, ext_id, val)?;
+        tx.commit()?;
+        Ok(result)
+    }
+
+    /// Returns information about per-extension usage
+    pub fn usage(&self) -> Result<Vec<crate::UsageInfo>> {
+        let db = self.db.lock();
+        api::usage(&db)
+    }
+
+    /// Returns the values for one or more keys `keys` can be:
+    ///
+    /// - `null`, in which case all key-value pairs for the extension are
+    ///   returned, or an empty object if the extension doesn't have any
+    ///   stored data.
+    /// - A single string key, in which case an object with only that key
+    ///   and its value is returned, or an empty object if the key doesn't
+    //    exist.
+    /// - An array of string keys, in which case an object with only those
+    ///   keys and their values is returned. Any keys that don't exist will be
+    ///   omitted.
+    /// - An object where the property names are keys, and each value is the
+    ///   default value to return if the key doesn't exist.
+    ///
+    /// This method always returns an object (that is, a
+    /// `serde_json::Value::Object`).
+    pub fn get(&self, ext_id: &str, keys: JsonValue) -> Result<JsonValue> {
+        // Don't care about transactions here.
+        let db = self.db.lock();
+        api::get(&db, ext_id, keys)
+    }
+
+    /// Deletes the values for one or more keys. As with `get`, `keys` can be
+    /// either a single string key, or an array of string keys. Returns a list
+    /// of changes, where each change contains the old value for each deleted
+    /// key.
+    pub fn remove(&self, ext_id: &str, keys: JsonValue) -> Result<StorageChanges> {
+        let db = self.db.lock();
+        let tx = db.unchecked_transaction()?;
+        let result = api::remove(&tx, ext_id, keys)?;
+        tx.commit()?;
+        Ok(result)
+    }
+
+    /// Deletes all key-value pairs for the extension. As with `remove`, returns
+    /// a list of changes, where each change contains the old value for each
+    /// deleted key.
+    pub fn clear(&self, ext_id: &str) -> Result<StorageChanges> {
+        let db = self.db.lock();
+        let tx = db.unchecked_transaction()?;
+        let result = api::clear(&tx, ext_id)?;
+        tx.commit()?;
+        Ok(result)
+    }
+
+    /// Returns the bytes in use for the specified items (which can be null,
+    /// a string, or an array)
+    pub fn get_bytes_in_use(&self, ext_id: &str, keys: JsonValue) -> Result<usize> {
+        let db = self.db.lock();
+        api::get_bytes_in_use(&db, ext_id, keys)
+    }
+
+    /// Returns a bridged sync engine for Desktop for this store.
+    pub fn bridged_engine(&self) -> sync::BridgedEngine {
+        sync::BridgedEngine::new(&self.db)
+    }
+
+    /// Closes the store and its database connection. See the docs for
+    /// `StorageDb::close` for more details on when this can fail.
+    pub fn close(self) -> Result<()> {
+        // Even though this consumes `self`, the fact we use an Arc<> means
+        // we can't guarantee we can actually consume the inner DB - so do
+        // the best we can.
+        let shared: ThreadSafeStorageDb = match Arc::try_unwrap(self.db) {
+            Ok(shared) => shared,
+            _ => {
+                // The only way this is possible is if the sync engine has an operation
+                // running - but that shouldn't be possible in practice because desktop
+                // uses a single "task queue" such that the close operation can't possibly
+                // be running concurrently with any sync or storage tasks.
+
+                // If this *could* get hit, rusqlite will attempt to close the DB connection
+                // as it is dropped, and if that close fails, then rusqlite 0.28.0 and earlier
+                // would panic - but even that only happens if prepared statements are
+                // not finalized, which ruqlite also does.
+
+                // tl;dr - this should be impossible. If it was possible, rusqlite might panic,
+                // but we've never seen it panic in practice other places we don't close
+                // connections, and the next rusqlite version will not panic anyway.
+                // So this-is-fine.jpg
+                log::warn!("Attempting to close a store while other DB references exist.");
+                return Err(ErrorKind::OtherConnectionReferencesExist.into());
+            }
+        };
+        // consume the mutex and get back the inner.
+        let db = shared.into_inner();
+        db.close()
+    }
+
+    /// Gets the changes which the current sync applied. Should be used
+    /// immediately after the bridged engine is told to apply incoming changes,
+    /// and can be used to notify observers of the StorageArea of the changes
+    /// that were applied.
+    /// The result is a Vec of already JSON stringified changes.
+    pub fn get_synced_changes(&self) -> Result<Vec<sync::SyncedExtensionChange>> {
+        let db = self.db.lock();
+        sync::get_synced_changes(&db)
+    }
+
+    /// Migrates data from a database in the format of the "old" kinto
+    /// implementation. Information about how the migration went is stored in
+    /// the database, and can be read using `Self::take_migration_info`.
+    ///
+    /// Note that `filename` isn't normalized or canonicalized.
+    pub fn migrate(&self, filename: impl AsRef<Path>) -> Result<()> {
+        let db = self.db.lock();
+        let tx = db.unchecked_transaction()?;
+        let result = migrate(&tx, filename.as_ref())?;
+        tx.commit()?;
+        // Failing to store this information should not cause migration failure.
+        if let Err(e) = result.store(&db) {
+            debug_assert!(false, "Migration error: {:?}", e);
+            log::warn!("Failed to record migration telmetry: {}", e);
+        }
+        Ok(())
+    }
+
+    /// Read-and-delete (e.g. `take` in rust parlance, see Option::take)
+    /// operation for any MigrationInfo stored in this database.
+    pub fn take_migration_info(&self) -> Result<Option<MigrationInfo>> {
+        let db = self.db.lock();
+        let tx = db.unchecked_transaction()?;
+        let result = MigrationInfo::take(&tx)?;
+        tx.commit()?;
+        Ok(result)
+    }
+}
+
+#[cfg(test)]
+pub mod test {
+    use super::*;
+    #[test]
+    fn test_send() {
+        fn ensure_send<T: Send>() {}
+        // Compile will fail if not send.
+        ensure_send::<Store>();
+    }
+
+    pub fn new_mem_store() -> Store {
+        Store {
+            db: Arc::new(ThreadSafeStorageDb::new(crate::db::test::new_mem_db())),
+        }
+    }
+}