media: Prefer decrypting pipeline when CDM is attached

media/base/video_decoder_config.h

Index: media/base/video_decoder_config.h
diff --git a/media/base/video_decoder_config.h b/media/base/video_decoder_config.h
index 2d3d3fe972930850811c0e7717b41e6f621bf22d..42b64db7c0df71c3e3186c551c3dae71251ea488 100644
--- a/media/base/video_decoder_config.h
+++ b/media/base/video_decoder_config.h
@@ -15,6 +15,7 @@
 #include "media/base/encryption_scheme.h"
 #include "media/base/hdr_metadata.h"
 #include "media/base/media_export.h"
+#include "media/base/media_util.h"
 #include "media/base/video_codecs.h"
 #include "media/base/video_types.h"
 #include "ui/gfx/color_space.h"
@@ -119,6 +120,25 @@ class MEDIA_EXPORT VideoDecoderConfig {
   void set_hdr_metadata(const HDRMetadata& hdr_metadata);
   base::Optional<HDRMetadata> hdr_metadata() const;
 
+  // Sets the config to be encrypted or not encrypted manually. This can be

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

Ditto.

[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:
   VideoCodec codec_;
   VideoCodecProfile profile_;