adb: implement LZ4 compression.
Add support for LZ4 compression, which compresses and decompresses far
more quickly than brotli, at the cost of worse compression ratio.
`adb sync -d system` speeds (in MB/s) on aosp_blueline-eng:
none brotli lz4
USB 3.0 120 110 190
USB 2.0 38 75 63
Bug: https://issuetracker.google.com/150827486
Test: python3 -m unittest test_device.FileOperationsTest{Uncompressed,Brotli,LZ4}
Change-Id: Ibef6ac15a76b4e5dcd02d7fb9433cbb1c02b8382
diff --git a/adb/transport.h b/adb/transport.h
index b1984db..12803b5 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -88,6 +88,8 @@
extern const char* const kFeatureSendRecv2;
// adbd supports brotli for send/recv v2.
extern const char* const kFeatureSendRecv2Brotli;
+// adbd supports LZ4 for send/recv v2.
+extern const char* const kFeatureSendRecv2LZ4;
TransportId NextTransportId();