media: Prefer decrypting pipeline when CDM is attached

media/base/audio_decoder_config.cc

Index: media/base/audio_decoder_config.cc
diff --git a/media/base/audio_decoder_config.cc b/media/base/audio_decoder_config.cc
index 253c82b147c96b0304ce49d83ec7c4334bb78fdb..225f19a7f796c34c42c31e2dfcf78dd11f8181d5 100644
--- a/media/base/audio_decoder_config.cc
+++ b/media/base/audio_decoder_config.cc
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "media/base/limits.h"
+#include "media/base/media_util.h"
 
 namespace media {
 
@@ -95,4 +96,19 @@ std::string AudioDecoderConfig::AsHumanReadableString() const {
   return s.str();
 }
 
+void AudioDecoderConfig::SetIsEncrypted(bool is_encrypted) {
+  if (!is_encrypted) {
+    DCHECK(encryption_scheme_.is_encrypted()) << "Config is already clear.";
+    encryption_scheme_ = Unencrypted();
+  } else {
+    DCHECK(!encryption_scheme_.is_encrypted())
+        << "Config is already encrypted.";
+    // TODO(xhwang): This is only used to guide decoder selection, so set
+    // a common encryption scheme that should be supported by all decrypting
+    // decoders. We should be able to remove this when we support switching
+    // decoders at run time. See http://crbug.com/695595
+    encryption_scheme_ = AesCtrEncryptionScheme();
+  }
+}
+
 }  // namespace media