Allow media track switching.

media/base/fake_audio_renderer_sink.cc

Index: media/base/fake_audio_renderer_sink.cc
diff --git a/media/base/fake_audio_renderer_sink.cc b/media/base/fake_audio_renderer_sink.cc
index 48e448d5acb43161f2c1c8b94aca6506a3e28df7..2468491f08b8ddc3ee9c7092a64538a3912da97b 100644
--- a/media/base/fake_audio_renderer_sink.cc
+++ b/media/base/fake_audio_renderer_sink.cc
@@ -32,7 +32,7 @@ FakeAudioRendererSink::~FakeAudioRendererSink() {
 
 void FakeAudioRendererSink::Initialize(const AudioParameters& params,
                                        RenderCallback* callback) {
-  DCHECK_EQ(state_, kUninitialized);
+  DCHECK(state_ == kUninitialized || state_ == kStopped);
   DCHECK(!callback_);
   DCHECK(callback);