Add Common Encryption support to BMFF, including subsample decryption.

media/mp4/avc.cc

Index: media/mp4/avc.cc
diff --git a/media/mp4/avc.cc b/media/mp4/avc.cc
index faf9939cf966b1aa1769cf7624e6fd1005fe08ee..9896e2c366e0d396e458d0ef54b1807534c10c82 100644
--- a/media/mp4/avc.cc
+++ b/media/mp4/avc.cc
@@ -59,32 +59,30 @@ bool AVC::ConvertToAnnexB(int length_size, std::vector<uint8>* buffer) {
 }
 
 // static
-bool AVC::InsertParameterSets(const AVCDecoderConfigurationRecord& avc_config,
-                         std::vector<uint8>* buffer) {
+bool AVC::ConvertParameterSets(const AVCDecoderConfigurationRecord& avc_config,
+                               std::vector<uint8>* buffer) {
+  DCHECK(buffer->empty());
+  buffer->clear();
   int total_size = 0;
   for (size_t i = 0; i < avc_config.sps_list.size(); i++)
     total_size += avc_config.sps_list[i].size() + kAnnexBStartCodeSize;
   for (size_t i = 0; i < avc_config.pps_list.size(); i++)
     total_size += avc_config.pps_list[i].size() + kAnnexBStartCodeSize;
-
-  std::vector<uint8> temp;
-  temp.reserve(total_size);
+  buffer->reserve(total_size);
 
   for (size_t i = 0; i < avc_config.sps_list.size(); i++) {
-    temp.insert(temp.end(), kAnnexBStartCode,
+    buffer->insert(buffer->end(), kAnnexBStartCode,
                 kAnnexBStartCode + kAnnexBStartCodeSize);
-    temp.insert(temp.end(), avc_config.sps_list[i].begin(),
+    buffer->insert(buffer->end(), avc_config.sps_list[i].begin(),
                 avc_config.sps_list[i].end());
   }
 
   for (size_t i = 0; i < avc_config.pps_list.size(); i++) {
-    temp.insert(temp.end(), kAnnexBStartCode,
-                kAnnexBStartCode + kAnnexBStartCodeSize);
-    temp.insert(temp.end(), avc_config.pps_list[i].begin(),
-                avc_config.pps_list[i].end());
+    buffer->insert(buffer->end(), kAnnexBStartCode,
+                   kAnnexBStartCode + kAnnexBStartCodeSize);
+    buffer->insert(buffer->end(), avc_config.pps_list[i].begin(),
+                   avc_config.pps_list[i].end());
   }
-
-  buffer->insert(buffer->begin(), temp.begin(), temp.end());
   return true;
 }