Maybe it's part of an A Chord?
Who knows, you can't really hear it anyway.
Obviously you can all the notes in alternative places, but that's the only part I can't decide where I like playing it
Verse Riff
Pre Chorus
Fill 1
-Repeat Pre Chorus x1
-Repeat Riff 1 x2
-Repeat Pre Chorus x2
-Play Fill 1
-Play Riff 1 x2
-Repeat Riff 1/Fill 1 combo x2
-Repeat Pre Chorus x2
Riff 2
Riff 3
Repeat Riff 2 x2
Then just change the rhythm and play for another 2 bars