Fix incorrect AudioConverter setup for discrete channel layouts.

media/base/fake_audio_render_callback.cc

Index: media/base/fake_audio_render_callback.cc
diff --git a/media/base/fake_audio_render_callback.cc b/media/base/fake_audio_render_callback.cc
index 5a0979e9ea0203ff316dc53545ef6a0d6d32d09c..73d606ec3fb66f06f40e1584bc40c7a367ed1626 100644
--- a/media/base/fake_audio_render_callback.cc
+++ b/media/base/fake_audio_render_callback.cc
@@ -15,6 +15,7 @@ FakeAudioRenderCallback::FakeAudioRenderCallback(double step)
     : half_fill_(false),
       step_(step),
       last_audio_delay_milliseconds_(-1),
+      last_channel_count_(-1),
       volume_(1) {
   reset();
 }
@@ -24,6 +25,8 @@ FakeAudioRenderCallback::~FakeAudioRenderCallback() {}
 int FakeAudioRenderCallback::Render(AudioBus* audio_bus,
                                     int audio_delay_milliseconds) {
   last_audio_delay_milliseconds_ = audio_delay_milliseconds;
+  last_channel_count_ = audio_bus->channels();
+
   int number_of_frames = audio_bus->frames();
   if (half_fill_)
     number_of_frames /= 2;