[Sync] Move sync/{internal_api,syncable} into syncer namespace

sync/syncable/syncable_mock.h

Index: sync/syncable/syncable_mock.h
diff --git a/sync/syncable/syncable_mock.h b/sync/syncable/syncable_mock.h
index 82eac1a8260e6481bebec4f5d4e8d3b01a2ddb87..c7427925dc90df82ed8fe5bf82a19a49ee2a48df 100644
--- a/sync/syncable/syncable_mock.h
+++ b/sync/syncable/syncable_mock.h
@@ -15,8 +15,8 @@
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using syncable::Directory;
-using syncable::EntryKernel;
+namespace syncer {
+namespace syncable {
 
 class MockDirectory : public Directory {
  public:
@@ -43,6 +43,7 @@ class MockSyncableWriteTransaction : public syncable::WriteTransaction {
       const tracked_objects::Location& from_here, Directory *directory);
 };
 
+}  // namespace syncable
+}  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_SYNCABLE_MOCK_H_
-