Test fwrite returnval in wav_ola_test.cc to fix ubuntu compile warning.

media/tools/wav_ola_test.cc

 // Copyright (c) 2009 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.
 
 // This application is a test for AudioRendererAlgorithmOLA. It reads in a
 // specified wav file (so far only 8, 16 and 32 bit are supported) and uses
 // ARAO to scale the playback by a specified rate. Then it outputs the result
 // to the specified location. Command line calls should be as follows:
 //
 //    wav_ola_test RATE INFILE OUTFILE
@@ skipping 129 matching lines @@
     } else {
       bytes_written += bytes;
     }
   }
 
   // Seek back to the beginning of our output file and update the header.
   wav.chunk_size = 36 + bytes_written;
   wav.subchunk1_size = 16;
   wav.subchunk2_size = bytes_written;
   fseek(output.get(), 0, SEEK_SET);
-  fwrite(&wav, sizeof(wav), 1, output.get());
+  if (fwrite(&wav, sizeof(wav), 1, output.get()) < 1) {
+    LOG(ERROR) << "could not write wav header.";
+    return 1;
+  }
 
   return 0;
 }