Releasing the former Stadia file transfer tools

The tools allow efficient and fast synchronization of large directory
trees from a Windows workstation to a Linux target machine.

cdc_rsync* support efficient copy of files by using content-defined
chunking (CDC) to identify chunks within files that can be reused.

asset_stream_manager + cdc_fuse_fs support efficient streaming of a
local directory to a remote virtual file system based on FUSE. It also
employs CDC to identify and reuse unchanged data chunks.

common/testing_clock.cc

@@ -0,0 +1,44 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "common/testing_clock.h"
+
+#include "common/stopwatch.h"
+
+namespace cdc_ft {
+
+TestingSteadyClock::Timestamp TestingSteadyClock::Now() const {
+  const Timestamp prev_now = now_;
+  now_ += std::chrono::milliseconds(auto_advance_ms_);
+  return prev_now;
+}
+
+void TestingSteadyClock::Advance(int milliseconds) {
+  now_ += std::chrono::milliseconds(milliseconds);
+}
+
+void TestingSteadyClock::AutoAdvance(int milliseconds) {
+  auto_advance_ms_ = milliseconds;
+}
+
+TestingSystemClock::TestingSystemClock()
+    : now_(std::chrono::system_clock::now()) {}
+
+TestingSystemClock::Timestamp TestingSystemClock::Now() const { return now_; }
+
+void TestingSystemClock::Advance(int milliseconds) {
+  now_ += std::chrono::milliseconds(milliseconds);
+}
+
+}  // namespace cdc_ft