media: Prefer decrypting pipeline when CDM is attached

media/base/audio_decoder_config.h

Index: media/base/audio_decoder_config.h
diff --git a/media/base/audio_decoder_config.h b/media/base/audio_decoder_config.h
index 266de82d605277543a3fec40b2c5a8faec165266..4e5298bed8e92daeeee13ad5484db6b638f9a356 100644
--- a/media/base/audio_decoder_config.h
+++ b/media/base/audio_decoder_config.h
@@ -10,12 +10,14 @@
 #include <string>
 #include <vector>
 
+#include "base/logging.h"
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "media/base/audio_codecs.h"
 #include "media/base/channel_layout.h"
 #include "media/base/encryption_scheme.h"
 #include "media/base/media_export.h"
+#include "media/base/media_util.h"
 #include "media/base/sample_format.h"
 
 namespace media {
@@ -87,6 +89,25 @@ class MEDIA_EXPORT AudioDecoderConfig {
     return encryption_scheme_;
   }
 
+  // Sets the config to be encrypted or not encrypted manually. This can be

[DaleCurtis, 2017/02/24 18:03:50]

Can't use hacker_style() for such a big method; move to .cc and rename
SetIsEncrypted().

[xhwang, 2017/02/24 18:18:15]

Done.

+  // useful for decryptors that decrypts an encrypted stream to a clear stream,
+  // or for decoder selectors that wants to select decrypting decoders instead
+  // of clear decoders.
+  void set_is_encrypted(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();
+    }
+  }
+
  private:
   AudioCodec codec_;
   SampleFormat sample_format_;