[Sync] Add sync client and begin transition to use it for plumbing

The SyncClient will encapsulate any dependencies that the sync driver has on
external components. Eventually it will replace the
ProfileSyncComponentsFactory as the source of all injected dependencies. The
ProfileSyncComponentsFactory at that point will be used only for creating
SyncAPI specific components, and will replace the SyncAPIComponentFactory.

Note: this change introduces some duplication of interfaces in an effort to
minimize the amount of files touched. Follow up changes will clean things up
and make the barrier between SynClient and SyncApiComponentFactory
clearer.

BUG=512768,512832

Review URL: https://codereview.chromium.org/1277243003

Cr-Commit-Position: refs/heads/master@{#343795}

1 files changed, 12 insertions, 0 deletions

diff --git a/components/sync_driver/sync_client.cc b/components/sync_driver/sync_client.cc
new file mode 100644
index 0000000..d4122ad
--- /dev/null
+++ b/components/sync_driver/sync_client.cc
@@ -0,0 +1,12 @@
+// Copyright 2015 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.
+
+#include "components/sync_driver/sync_client.h"
+
+namespace sync_driver {
+
+SyncClient::SyncClient() {}
+SyncClient::~SyncClient() {}
+
+}  // namespace sync_driver