Fix off-by-one in ALSA control name determination.

media/audio/alsa/alsa_util.cc

 // Copyright 2013 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/audio/alsa/alsa_util.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "media/audio/alsa/alsa_wrapper.h"
@@ skipping 36 matching lines @@
   const char kMixerPrefix[] = "hw";
   std::string control_name;
   size_t pos1 = device_name.find(':');
   if (pos1 == std::string::npos) {
     control_name = device_name;
   } else {
     // Examples:
     // deviceName: "front:CARD=Intel,DEV=0", controlName: "hw:CARD=Intel".
     // deviceName: "default:CARD=Intel", controlName: "CARD=Intel".
     size_t pos2 = device_name.find(',');
-    control_name = (pos2 == std::string::npos) ?
-        device_name.substr(pos1) :
-        kMixerPrefix + device_name.substr(pos1, pos2 - pos1);
+    control_name = (pos2 == std::string::npos)
+                       ? device_name.substr(pos1 + 1)
+                       : kMixerPrefix + device_name.substr(pos1, pos2 - pos1);
   }
 
   return control_name;
 }
 
 snd_pcm_format_t BitsToFormat(int bits_per_sample) {
   switch (bits_per_sample) {
     case 8:
       return SND_PCM_FORMAT_U8;
 
@@ skipping 121 matching lines @@
       else if (strcmp(elem_name, kMicElemName) == 0)
         mic_elem = elem;
     }
   }
 
   // Did not find any Capture handle, use the Mic handle.
   return mic_elem;
 }
 
 }  // namespace alsa_util