Add data pipe wrappers to be used to implement serial receive.

device/serial/serial.gyp

Index: device/serial/serial.gyp
diff --git a/device/serial/serial.gyp b/device/serial/serial.gyp
index 304a9c348c03875841b66be7a7b16fbe65167eb5..ac1cced02d0e4bb8efe252cf50bb677eceba776c 100644
--- a/device/serial/serial.gyp
+++ b/device/serial/serial.gyp
@@ -19,6 +19,7 @@
       ],
       'sources': [
         'serial.mojom',
+        'data_pipe.mojom',
       ],
     },
     {
@@ -42,10 +43,18 @@
         '../../mojo/mojo_base.gyp:mojo_cpp_bindings',
       ],
       'sources': [
+        '<(SHARED_INTERMEDIATE_DIR)/device/serial/data_pipe.mojom.cc',
+        '<(SHARED_INTERMEDIATE_DIR)/device/serial/data_pipe.mojom.h',
         '<(SHARED_INTERMEDIATE_DIR)/device/serial/serial.mojom.cc',
         '<(SHARED_INTERMEDIATE_DIR)/device/serial/serial.mojom.h',
+        'async_waiter.cc',
+        'async_waiter.h',
         'buffer.cc',
         'buffer.h',
+        'data_pipe_producer.cc',
+        'data_pipe_producer.h',
+        'data_pipe_receiver.cc',
+        'data_pipe_receiver.h',
         'serial_connection.cc',
         'serial_connection.h',
         'serial_connection_factory.cc',