Fix for clang build warnings: undefined variables if !USE_UDEV.

media/midi/midi_manager_alsa.cc

 // Copyright 2014 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.
 
 #include "media/midi/midi_manager_alsa.h"
 
 #include <alsa/asoundlib.h>
 #include <stdlib.h>
 #include <algorithm>
 #include <string>
@@ skipping 25 matching lines @@
 
 // Minimum client id for which we will have ALSA card devices for. When we
 // are searching for card devices (used to get the path, id, and manufacturer),
 // we don't want to get confused by kernel clients that do not have a card.
 // See seq_clientmgr.c in the ALSA code for this.
 // TODO(agoode): Add proper client -> card export from the kernel to avoid
 //               hardcoding.
 const int kMinimumClientIdForCards = 16;
 
 // udev key constants.
+#if defined(USE_UDEV)
 const char kSoundClass[] = "sound";
 const char kIdVendor[] = "ID_VENDOR";
 const char kIdVendorEnc[] = "ID_VENDOR_ENC";
 const char kIdVendorFromDatabase[] = "ID_VENDOR_FROM_DATABASE";
 const char kSysattrVendorName[] = "vendor_name";
 const char kIdVendorId[] = "ID_VENDOR_ID";
 const char kSysattrVendor[] = "vendor";
 const char kIdModelId[] = "ID_MODEL_ID";
 const char kSysattrModel[] = "model";
 const char kIdBus[] = "ID_BUS";
 const char kIdPath[] = "ID_PATH";
 const char kUsbInterfaceNum[] = "ID_USB_INTERFACE_NUM";
+#endif  // defined(USE_UDEV)
 
 // ALSA constants.
 const char kAlsaHw[] = "hw";
 
 // Constants for the capabilities we search for in inputs and outputs.
 // See http://www.alsa-project.org/alsa-doc/alsa-lib/seq.html.
 const unsigned int kRequiredInputPortCaps =
     SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ;
 const unsigned int kRequiredOutputPortCaps =
     SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE;
@@ skipping 657 matching lines @@
       }
     }
   }
 }
 
 MidiManager* MidiManager::Create() {
   return new MidiManagerAlsa();
 }
 
 }  // namespace media