Reland "Supporting 48kHz PCM file."

This was first reviewed in https://codereview.webrtc.org/2790493004/.

It got reverted in https://codereview.webrtc.org/2791453004/ due to
upstreaming error.

Bug: None
TBR: niklas.enbom@webrtc.org
Change-Id: Ia5e9bf86e004258b2aa7822bd489d357fcb8f906
Reviewed-on: https://chromium-review.googlesource.com/645634
Reviewed-by: Minyue Li (BackIn2018March) <minyue@webrtc.org>
Commit-Queue: Minyue Li (BackIn2018March) <minyue@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19642}
diff --git a/webrtc/common_types.h b/webrtc/common_types.h
index ac5c2e2..868bee4 100644
--- a/webrtc/common_types.h
+++ b/webrtc/common_types.h
@@ -142,7 +142,8 @@
   kFileFormatPreencodedFile = 4,
   kFileFormatPcm16kHzFile = 7,
   kFileFormatPcm8kHzFile = 8,
-  kFileFormatPcm32kHzFile = 9
+  kFileFormatPcm32kHzFile = 9,
+  kFileFormatPcm48kHzFile = 10
 };
 
 enum FrameType {