Switch LevelDBWrapper::GetAll to use the new Mojo sync IPC mechanism.

content/common/leveldb_wrapper.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module content;
 
 import "components/leveldb/public/interfaces/leveldb.mojom";
 
 struct KeyValue {
   array<uint8> key;
@@ skipping 12 matching lines @@
   // did not exist in the database.
   Delete(array<uint8> key, string source) => (leveldb.DatabaseError status);
 
   // Removes all the entries.
   DeleteAll(string source) => (leveldb.DatabaseError status);
 
   // Returns the value of the given key.
   Get(array<uint8> key) => (leveldb.DatabaseError status, array<uint8> value);
 
   // Only used with small databases. Returns all key/value pairs.
+  [Sync]
   GetAll() => (leveldb.DatabaseError status, array<KeyValue> data);
 };
 
 // Gives information about changes to a LevelDB database.
 interface LevelDBObserver {
   KeyChanged(array<uint8> key, array<uint8> new_value, array<uint8> old_value,
              string source);
   KeyDeleted(array<uint8> key, string source);
   AllDeleted(string source);
 };