ChannelMojo should use PID from the bootstrap Channel.

ipc/mojo/ipc_mojo_bootstrap.cc

Index: ipc/mojo/ipc_mojo_bootstrap.cc
diff --git a/ipc/mojo/ipc_mojo_bootstrap.cc b/ipc/mojo/ipc_mojo_bootstrap.cc
index 591ced067e98694d2e3a2021545ea422d928b945..e449577dcb3317e505a0ffe2cf27332b0226245b 100644
--- a/ipc/mojo/ipc_mojo_bootstrap.cc
+++ b/ipc/mojo/ipc_mojo_bootstrap.cc
@@ -200,6 +200,10 @@ bool MojoBootstrap::Connect() {
   return channel_->Connect();
 }
 
+base::ProcessId MojoBootstrap::GetSelfPID() const {
+  return channel_->GetSelfPID();
+}
+
 void MojoBootstrap::OnBadMessageReceived(const Message& message) {
   Fail();
 }