media config: expand is_encrypted to a struct.

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 a0e262f005d3343279ac3e5fa137549d4a203db8..022f96536fb475123c46e3cb3037482fbf4f1fc6 100644
--- a/media/base/audio_decoder_config.h
+++ b/media/base/audio_decoder_config.h
@@ -13,6 +13,7 @@
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "media/base/channel_layout.h"
+#include "media/base/encryption_scheme.h"
 #include "media/base/media_export.h"
 #include "media/base/sample_format.h"
 
@@ -66,7 +67,7 @@ class MEDIA_EXPORT AudioDecoderConfig {
                      ChannelLayout channel_layout,
                      int samples_per_second,
                      const std::vector<uint8_t>& extra_data,
-                     bool is_encrypted);
+                     const EncryptionScheme& encryption_scheme);
 
   ~AudioDecoderConfig();
 
@@ -76,7 +77,7 @@ class MEDIA_EXPORT AudioDecoderConfig {
                   ChannelLayout channel_layout,
                   int samples_per_second,
                   const std::vector<uint8_t>& extra_data,
-                  bool is_encrypted,
+                  const EncryptionScheme& encryption_scheme,
                   base::TimeDelta seek_preroll,
                   int codec_delay);
 
@@ -109,7 +110,12 @@ class MEDIA_EXPORT AudioDecoderConfig {
   // Whether the audio stream is potentially encrypted.
   // Note that in a potentially encrypted audio stream, individual buffers
   // can be encrypted or not encrypted.
-  bool is_encrypted() const { return is_encrypted_; }
+  bool is_encrypted() const;

[ddorwin, 2016/03/01 02:17:41]

My concern in PS1 of cast_audio_output_stream_unittest.cc was really about this
change (and the corresponding one for video).

We may have tests calling is_encrypted() on the config, and these will continue
to compile without changes. However, we really should be checking all properties
of the scheme. We should try to identify and update those tests.

[dougsteed, 2016/03/02 18:07:52]

It seems to me that generally in the code (there are 67 places in 30 files where
is_encrypted() is called) the caller is interested in just the boolean, not the
details. For example, in many contexts, both in the actual code and in
unittests, encryption is not allowed or supported, so being able to test that
is_encrypted() is false seems very appropriate. In those contexts there is
nothing to be gained in checking the mode or pattern.

[ddorwin, 2016/03/02 23:24:05]

Okay. I guess we should look for places where we expect it to be true in tests
and then check the other members in those cases.

+
+  // Encryption scheme used for encrypted buffers.
+  const EncryptionScheme& encryption_scheme() const {
+    return encryption_scheme_;
+  }
 
  private:
   AudioCodec codec_;
@@ -119,7 +125,7 @@ class MEDIA_EXPORT AudioDecoderConfig {
   int samples_per_second_;
   int bytes_per_frame_;
   std::vector<uint8_t> extra_data_;
-  bool is_encrypted_;
+  EncryptionScheme encryption_scheme_;
 
   // |seek_preroll_| is the duration of the data that the decoder must decode
   // before the decoded data is valid.