Clean up histogram'd media enum max values.

media/audio/linux/audio_manager_linux.cc

 // Copyright (c) 2012 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 "base/command_line.h"
 #include "base/metrics/histogram.h"
 #if defined(USE_ALSA)
 #include "media/audio/alsa/audio_manager_alsa.h"
 #else
 #include "media/audio/fake_audio_manager.h"
 #endif
 #if defined(USE_CRAS)
 #include "media/audio/cras/audio_manager_cras.h"
 #endif
 #if defined(USE_PULSEAUDIO)
 #include "media/audio/pulse/audio_manager_pulse.h"
 #endif
 #include "media/base/media_switches.h"
 
 namespace media {
 
 enum LinuxAudioIO {
   kPulse,
   kAlsa,
   kCras,
-  kAudioIOMax  // Must always be last!
+  kAudioIOMax = kCras  // Must always be equal to last entry!
 };
 
 AudioManager* CreateAudioManager(AudioLogFactory* audio_log_factory) {
 #if defined(USE_CRAS)
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kUseCras)) {
-    UMA_HISTOGRAM_ENUMERATION("Media.LinuxAudioIO", kCras, kAudioIOMax);
+    UMA_HISTOGRAM_ENUMERATION("Media.LinuxAudioIO", kCras, kAudioIOMax + 1);
     return new AudioManagerCras(audio_log_factory);
   }
 #endif
 
 #if defined(USE_PULSEAUDIO)
   AudioManager* manager = AudioManagerPulse::Create(audio_log_factory);
   if (manager) {
-    UMA_HISTOGRAM_ENUMERATION("Media.LinuxAudioIO", kPulse, kAudioIOMax);
+    UMA_HISTOGRAM_ENUMERATION("Media.LinuxAudioIO", kPulse, kAudioIOMax + 1);
     return manager;
   }
 #endif
 
 #if defined(USE_ALSA)
-  UMA_HISTOGRAM_ENUMERATION("Media.LinuxAudioIO", kAlsa, kAudioIOMax);
+  UMA_HISTOGRAM_ENUMERATION("Media.LinuxAudioIO", kAlsa, kAudioIOMax + 1);
   return new AudioManagerAlsa(audio_log_factory);
 #else
   return new FakeAudioManager(audio_log_factory);
 #endif
 }
 
 }  // namespace media