[mojo-edk]: zero message buffer on allocation

mojo/edk/system/channel.cc

Index: mojo/edk/system/channel.cc
diff --git a/mojo/edk/system/channel.cc b/mojo/edk/system/channel.cc
index bfb8c32dcfea20551fc4ce6a106a5605297fa496..2d6142e3a6abc4d1741e2d0b491b6893b8b5b813 100644
--- a/mojo/edk/system/channel.cc
+++ b/mojo/edk/system/channel.cc
@@ -38,6 +38,7 @@ Channel::Message::Message(size_t payload_size,
 
   data_ = static_cast<char*>(base::AlignedAlloc(size_,
                                                 kChannelMessageAlignment));
+  memset(data_, 0, size_);
   header_ = reinterpret_cast<Header*>(data_);
 
   DCHECK_LE(size_, std::numeric_limits<uint32_t>::max());