relnote: Cache-align the encryption buffer in QuicPacketCreator::SerializePacket.

net/quic/quic_packet_creator.cc

Index: net/quic/quic_packet_creator.cc
diff --git a/net/quic/quic_packet_creator.cc b/net/quic/quic_packet_creator.cc
index 3dcfe6e06b98f9bdb435b298b4136c6fb9cdec03..5c2c644f6b52361becc8fe5b88229c3f8794feef 100644
--- a/net/quic/quic_packet_creator.cc
+++ b/net/quic/quic_packet_creator.cc
@@ -450,7 +450,11 @@ SerializedPacket QuicPacketCreator::SerializePacket(
   bool possibly_truncated_by_length = packet_size_ == max_plaintext_size_ &&
                                       queued_frames_.size() == 1 &&
                                       queued_frames_.back().type == ACK_FRAME;
-  char buffer[kMaxPacketSize];
+  // The optimized encryption algorithm implementations run faster when
+  // operating on aligned memory.
+  // TODO(rtenneti): Change the default 64 alignas value (used the default
+  // value from CACHELINE_SIZE).
+  ALIGNAS(64) char buffer[kMaxPacketSize];
   scoped_ptr<QuicPacket> packet;
   // Use the packet_size_ instead of the buffer size to ensure smaller
   // packet sizes are properly used.