Revert of Update device/usb and its Mojo interface for variable size ISO packets.

device/devices_app/usb/public/interfaces/device.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module device.usb;
 
 enum OpenDeviceError {
   // Opening the device succeeded.
   OK,
 
@@ skipping 121 matching lines @@
 
   // The transfer succeeded, but the device sent more data than was requested.
   // This applies only to inbound transfers.
   BABBLE,
 
   // The transfer succeeded, but the device sent less data than was requested.
   // This applies only to inbound transfers.
   SHORT_PACKET,
 };
 
-struct IsochronousPacket {
-  uint32 length;
-  uint32 transferred_length;
-  TransferStatus status;
-};
-
 interface Device {
   // Retrieve a DeviceInfo struct containing metadata about the device,
   // including the set of all available device configurations.
   GetDeviceInfo() => (DeviceInfo? info);
 
   // Retrieves the |configuration_value| of the device's currently active
   // configuration. Will return 0 if the device is unconfigured.
   GetConfiguration() => (uint8 value);
 
   // Opens the device. Methods below require the device be opened first.
@@ skipping 79 matching lines @@
   // completed or otherwise terminated.
   GenericTransferOut(uint8 endpoint_number, array<uint8> data, uint32 timeout)
       => (TransferStatus status);
 
   // Initiates an inbound isochronous transfer request on a specific endpoint.
   // The interface to which |endpoint_number| belongs must be claimed, and the
   // appropriate alternate setting must be set on that interface before
   // transfers can be initiated on the endpoint. The endpoint must be of type
   // ISOCHRONOUS.
   //
-  // |packet_lengths| specifies the maximum expected number of bytes to receive
-  // for each packet in this transfer.
+  // |packet_length| specifies the maximum expected number of bytes to receive
+  // for each packet in this transfer. |num_packets| specifies the maximum total
+  // number of packets to receive.
   //
   // |timeout| specifies the request timeout in milliseconds. A timeout of 0
   // indicates no timeout: the request will remain pending indefinitely until
   // completed or otherwise terminated.
   //
-  // |data| contains the data received from the device, if any. |packets|
-  // contains the status of each packet received from the device, in order. The
-  // length of the packet indicates its position in |data| while it's
-  // transferred length gives the amount of data actually received from the
-  // device.
+  // |packets| contains the set of packets received from the device, in order.
+  // No received packet's size will exceed |packet_length|, and will be null
+  // if |status| is neither COMPLETED, BABBLE, or SHORT_PACKET.
   IsochronousTransferIn(uint8 endpoint_number,
-                        array<uint32> packet_lengths,
+                        uint32 num_packets,
+                        uint32 packet_length,
                         uint32 timeout)
-      => (array<uint8>? data, array<IsochronousPacket> packets);
+      => (TransferStatus status, array<array<uint8>>? packets);
 
   // Initiates an outbound isochronous transfer request on a specific endpoint.
   // The interface to which |endpoint_number| belongs must be claimed, and the
   // appropriate alternate setting must be set on that interface before
   // transfers can be initiated on the endpoint. The endpoint must be of type
   // ISOCHRONOUS.
   //
-  // |data| specifies the bytes to send to the device.
-  //
-  // |packet_lengths| specifies how |data| should be separated into packets when
-  // it is sent to the device.
+  // |packets| specifies the series of data packets to send to the device for
+  // this transfer.
   //
   // |timeout| specifies the request timeout in milliseconds. A timeout of 0
   // indicates no timeout: the request will remain pending indefinitely until
   // completed or otherwise terminated.
-
-  // |packets| contains the status of each packet sent to the device, in order.
   IsochronousTransferOut(uint8 endpoint_number,
-                         array<uint8> data,
-                         array<uint32> packet_lengths,
+                         array<array<uint8>> packets,
                          uint32 timeout)
-      => (array<IsochronousPacket> packets);
+      => (TransferStatus status);
 };