Add vector_math::FMUL. Replace audio_util::AdjustVolume.

media/base/vector_math.h

Index: media/base/vector_math.h
diff --git a/media/base/vector_math.h b/media/base/vector_math.h
index 10c3039d805fd93502c3ddcd22fc648b5446441d..2618687ec142cdd8888e39a0aee7a193da108131 100644
--- a/media/base/vector_math.h
+++ b/media/base/vector_math.h
@@ -17,6 +17,10 @@ enum { kRequiredAlignment = 16 };
 // |src| and |dest| must be aligned by kRequiredAlignment.
 MEDIA_EXPORT void FMAC(const float src[], float scale, int len, float dest[]);
 
+// Multiply each element of |src| by |scale| and store in |dest|.  |src| and
+// |dest| must be aligned by kRequiredAlignment.
+MEDIA_EXPORT void FMUL(const float src[], float scale, int len, float dest[]);
+
 }  // namespace vector_math
 }  // namespace media