webm2pes: Track total bytes written.

Change-Id: I78807280cbd05f642215c83d5db4d04837c06438
diff --git a/m2ts/webm2pes.cc b/m2ts/webm2pes.cc
index 8402ca8..4cb6139 100644
--- a/m2ts/webm2pes.cc
+++ b/m2ts/webm2pes.cc
@@ -260,6 +260,7 @@
             std::fprintf(stderr, "Webm2Pes: packet payload write failed.\n");
             return false;
           }
+          bytes_written_ += packet_data_.size();
         }
       }
       block_status = cluster->GetNext(block_entry, block_entry);
@@ -325,6 +326,7 @@
             std::fprintf(stderr, "Webm2Pes: ReceivePacket failed.\n");
             return false;
           }
+          bytes_written_ += packet_data_.size();
         }
       }
       block_status = cluster->GetNext(block_entry, block_entry);
diff --git a/m2ts/webm2pes.h b/m2ts/webm2pes.h
index 9db0cb5..6dcb0fd 100644
--- a/m2ts/webm2pes.h
+++ b/m2ts/webm2pes.h
@@ -224,6 +224,8 @@
   static bool WritePesPacket(const VideoFrame& frame,
                              PacketDataBuffer* packet_data);
 
+  uint64_t bytes_written() const { return bytes_written_; }
+
  private:
   bool InitWebmParser();
   bool ReadVideoFrame(const mkvparser::Block::Frame& mkvparser_frame,
@@ -250,6 +252,8 @@
   PacketReceiverInterface* packet_sink_ = nullptr;
 
   PacketDataBuffer packet_data_;
+
+  std::uint64_t bytes_written_ = 0;
 };
 
 // Copies |raw_input_length| bytes from |raw_input| to |packet_buffer| while