Use safer IPC serializations in media_param_traits.cc

media/audio/audio_parameters.h

Index: media/audio/audio_parameters.h
diff --git a/media/audio/audio_parameters.h b/media/audio/audio_parameters.h
index 9267232acf9a5705f35004766450021178b1e1c3..3820d8cc3c91de2f3f7168d58074d2b25f8a4072 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -33,10 +33,10 @@ class MEDIA_EXPORT AudioParameters {
   // TODO(miu): Rename this enum to something that correctly reflects its
   // semantics, such as "TransportScheme."
   enum Format {
-    AUDIO_PCM_LINEAR = 0,     // PCM is 'raw' amplitude samples.
-    AUDIO_PCM_LOW_LATENCY,    // Linear PCM, low latency requested.
-    AUDIO_FAKE,               // Creates a fake AudioOutputStream object.
-    AUDIO_LAST_FORMAT         // Only used for validation of format.
+    AUDIO_PCM_LINEAR = 0,            // PCM is 'raw' amplitude samples.
+    AUDIO_PCM_LOW_LATENCY,           // Linear PCM, low latency requested.
+    AUDIO_FAKE,                      // Creates a fake AudioOutputStream object.
+    AUDIO_FORMAT_LAST = AUDIO_FAKE,  // Only used for validation of format.
   };
 
   enum {