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.

metrics/BUILD

@@ -0,0 +1,49 @@
+package(default_visibility = ["//:__subpackages__"])
+
+cc_library(
+    name = "metrics",
+    srcs = [
+        "metrics.cc",
+    ],
+    hdrs = [
+        "metrics.h",
+    ],
+    deps = [
+        ":enums",
+        ":messages",
+        "//common:log",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/strings:str_format",
+    ],
+)
+
+cc_library(
+    name = "enums",
+    hdrs = ["enums.h"],
+)
+
+cc_library(
+    name = "messages",
+    srcs = ["messages.cc"],
+    hdrs = ["messages.h"],
+    deps = [
+        ":enums",
+        "@com_google_absl//absl/status",
+    ],
+)
+
+cc_test(
+    name = "messages_test",
+    srcs = ["messages_test.cc"],
+    deps = [
+        ":messages",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+filegroup(
+    name = "all_test_sources",
+    srcs = glob(["*_test.cc"]),
+)