[Chromecast] Add a return value after NOTREACHED in tests.

chromecast/media/audio/cast_audio_output_stream_unittest.cc

 // Copyright 2015 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 "chromecast/base/task_runner_impl.h"
 #include "chromecast/media/audio/cast_audio_manager.h"
 #include "chromecast/media/audio/cast_audio_output_stream.h"
 #include "chromecast/public/media/audio_pipeline_device.h"
 #include "chromecast/public/media/cast_decoder_buffer.h"
 #include "chromecast/public/media/decoder_config.h"
@@ skipping 62 matching lines @@
     last_frame_completion_cb_.reset(completion_cb);
     ++pushed_frame_count_;
 
     switch (pipeline_status_) {
       case PIPELINE_STATUS_OK:
         return kFrameSuccess;
       case PIPELINE_STATUS_BUSY:
         return kFramePending;
       case PIPELINE_STATUS_ERROR:
         return kFrameFailed;
+      default:
+        NOTREACHED();
     }
-    NOTREACHED();
+
+    // This will never be reached but is necessary for compiler warnings.
+    return kFrameFailed;
   }
   RenderingDelay GetRenderingDelay() const override { return RenderingDelay(); }
   bool GetStatistics(Statistics* stats) const override { return false; }
   bool SetConfig(const AudioConfig& config) override {
     config_ = config;
     return true;
   }
   void SetStreamVolumeMultiplier(float multiplier) override {
     volume_multiplier_ = multiplier;
   }
@@ skipping 391 matching lines @@
   stream->GetVolume(&volume);
   EXPECT_EQ(0.5, volume);
   EXPECT_EQ(0.5f, audio_device->volume_multiplier());
 
   stream->Close();
 }
 
 }  // namespace
 }  // namespace media
 }  // namespace chromecast