Add Common Encryption support to BMFF, including subsample decryption.

media/base/decrypt_config.cc

Index: media/base/decrypt_config.cc
diff --git a/media/base/decrypt_config.cc b/media/base/decrypt_config.cc
index 9ae5f195e5d4cfab2be9a45108b23d329d2732e4..fb3385a219aef24684205964d6cbbd0891d39a3c 100644
--- a/media/base/decrypt_config.cc
+++ b/media/base/decrypt_config.cc
@@ -8,8 +8,25 @@
 
 namespace media {
 
+// TODO(strobe): Remove along with CBC mode.
+static const char kDefaultIv[] = "0000000000000000";
+
 DecryptConfig::DecryptConfig(const uint8* key_id, int key_id_size)
-    : key_id_size_(key_id_size) {
+    : key_id_size_(key_id_size),
+      iv_(kDefaultIv),
+      use_cbc_(true) {
+  CHECK_GT(key_id_size, 0);
+  key_id_.reset(new uint8[key_id_size]);
+  memcpy(key_id_.get(), key_id, key_id_size);
+}
+
+DecryptConfig::DecryptConfig(const uint8* key_id, int key_id_size,
+                             const std::string& iv,
+                             const std::vector<SubsampleEntry>& subsamples)
+    : key_id_size_(key_id_size),
+      iv_(iv),
+      subsamples_(subsamples),
+      use_cbc_(false) {
   CHECK_GT(key_id_size, 0);
   key_id_.reset(new uint8[key_id_size]);
   memcpy(key_id_.get(), key_id, key_id_size);