Add dedicated PipelineStatus UMAs for encrypted playback

media/filters/decrypting_video_decoder.cc

Index: media/filters/decrypting_video_decoder.cc
diff --git a/media/filters/decrypting_video_decoder.cc b/media/filters/decrypting_video_decoder.cc
index 4a14bad5dcd31c8bf061897be6c1a4c570e6eed3..8b105fea2b1bb234c2cd6c7c52a96b718c0fdb1c 100644
--- a/media/filters/decrypting_video_decoder.cc
+++ b/media/filters/decrypting_video_decoder.cc
@@ -19,6 +19,8 @@
 
 namespace media {
 
+const char DecryptingVideoDecoder::kDecoderName[] = "DecryptingVideoDecoder";
+
 DecryptingVideoDecoder::DecryptingVideoDecoder(
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
     const SetDecryptorReadyCB& set_decryptor_ready_cb)
@@ -31,7 +33,7 @@ DecryptingVideoDecoder::DecryptingVideoDecoder(
       weak_factory_(this) {}
 
 std::string DecryptingVideoDecoder::GetDisplayName() const {
-  return "DecryptingVideoDecoder";
+  return kDecoderName;
 }
 
 void DecryptingVideoDecoder::Initialize(const VideoDecoderConfig& config,