Allow sample rate pass through on Linux.

media/audio/pulse/audio_manager_pulse.cc

Index: media/audio/pulse/audio_manager_pulse.cc
diff --git a/media/audio/pulse/audio_manager_pulse.cc b/media/audio/pulse/audio_manager_pulse.cc
index c127d179c624d9d66a0c6e02f107a1f41794c724..fed919a333382558459542a8f73a47df69f965f0 100644
--- a/media/audio/pulse/audio_manager_pulse.cc
+++ b/media/audio/pulse/audio_manager_pulse.cc
@@ -141,11 +141,15 @@ AudioParameters AudioManagerPulse::GetPreferredOutputStreamParameters(
   int buffer_size = kDefaultOutputBufferSize;
   int bits_per_sample = 16;
   int input_channels = 0;
+  int sample_rate;
   if (input_params.IsValid()) {
     bits_per_sample = input_params.bits_per_sample();
     channel_layout = input_params.channel_layout();
     input_channels = input_params.input_channels();
     buffer_size = std::min(buffer_size, input_params.frames_per_buffer());
+    sample_rate = input_params.sample_rate();
+  } else {
+    sample_rate = GetNativeSampleRate();
   }
 
   int user_buffer_size = GetUserBufferSize();
@@ -154,7 +158,7 @@ AudioParameters AudioManagerPulse::GetPreferredOutputStreamParameters(
 
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout, input_channels,
-      GetNativeSampleRate(), bits_per_sample, buffer_size);
+      sample_rate, bits_per_sample, buffer_size);
 }
 
 AudioOutputStream* AudioManagerPulse::MakeOutputStream(