media/audio/linux: Add CrasInputStream.

media/audio/linux/audio_manager_linux.cc

Index: media/audio/linux/audio_manager_linux.cc
diff --git a/media/audio/linux/audio_manager_linux.cc b/media/audio/linux/audio_manager_linux.cc
index 0b34aaa81186e0e6a491895c8364c5817cab0e39..bd555f1ab21c8992424a6ac48ed0f823b9aff351 100644
--- a/media/audio/linux/audio_manager_linux.cc
+++ b/media/audio/linux/audio_manager_linux.cc
@@ -18,6 +18,7 @@
 #include "media/audio/pulse/pulse_output.h"
 #endif
 #if defined(USE_CRAS)
+#include "media/audio/linux/cras_input.h"
 #include "media/audio/linux/cras_output.h"
 #endif
 #include "media/base/limits.h"
@@ -297,7 +298,13 @@ AudioOutputStream* AudioManagerLinux::MakeOutputStream(
 
 AudioInputStream* AudioManagerLinux::MakeInputStream(
     const AudioParameters& params, const std::string& device_id) {
+  AudioInputStream* stream = NULL;
 
+#if defined(USE_CRAS)
+  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kUseCras)) {
+    stream = new CrasInputStream(params, this);

[no longer working on chromium, 2012/06/20 10:45:26]

btw, do you support device selection? or any plan to support it?

[dgreid, 2012/06/20 17:14:25]

The hope is that ChromeOS automatically selecting the most recently attached
device will satisfy most use cases.  Therefor there is not UI exposed to switch
devices, but it works from the command line, so adding it won't be difficult if
necessary. 

+  } else {

[no longer working on chromium, 2012/06/20 10:45:26]

Why do we need the else case, it is a bit hard to read.
Do we really need to DCHECK below, if not, how about changing it to:
#if defined(USE_CRAS)
if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kUseCras)) {
  return new CrasInputStream(params, this);
#endif

[dgreid, 2012/06/20 17:14:25]

Good suggestion, I also took the opportunity to modify the related
MakeOutputStream().

+#endif
   std::string device_name = (device_id == AudioManagerBase::kDefaultDeviceId) ?
       AlsaPcmInputStream::kAutoSelectDevice : device_id;
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kAlsaInputDevice)) {
@@ -305,7 +312,13 @@ AudioInputStream* AudioManagerLinux::MakeInputStream(
         switches::kAlsaInputDevice);
   }
 
-  return new AlsaPcmInputStream(this, device_name, params, wrapper_.get());
+  stream = new AlsaPcmInputStream(this, device_name, params, wrapper_.get());
+#if defined(USE_CRAS)
+  }
+#endif
+
+  DCHECK(stream);
+  return stream;
 }
 
 AudioManager* CreateAudioManager() {