Motown: Fix unique_ptrs to arrays so deallocation is done properly

services/media/audio/platform/generic/standard_output_base.h

Index: services/media/audio/platform/generic/standard_output_base.h
diff --git a/services/media/audio/platform/generic/standard_output_base.h b/services/media/audio/platform/generic/standard_output_base.h
index fd692fb521546bba1b399e607aaf6bd3871da8ac..60db6e0b4546c90ceec454253e0a55188a67fd5d 100644
--- a/services/media/audio/platform/generic/standard_output_base.h
+++ b/services/media/audio/platform/generic/standard_output_base.h
@@ -115,7 +115,7 @@ class StandardOutputBase : public AudioOutput {
   //    will drop to only 255 simultanious tracks.  It is unclear if this is a
   //    reasonable system-wide limitation or not.
   // 2) We support floating point audio.
-  std::unique_ptr<int32_t> mix_buf_;
+  std::unique_ptr<int32_t[]> mix_buf_;
   uint32_t mix_buf_frames_ = 0;
 
   // State used by the mix task.