[AutoComplete] Dropdown icon not centered-aligned when variant="filled"

[eyalito]

Current Behavior 😯

When AutoComplete has <TextField variant="filled ... />, dropdown icon is not centered-aligned. (screenshot from AutoComplete demo: https://codesandbox.io/s/material-demo-9zn53)

Expected Behavior 🤔

Dropdown icon is centered-align as in with <TextField variant="contained" ... />.

Steps to Reproduce 🕹

Steps:

1. go to https://codesandbox.io/s/material-demo-9zn53
2. select 'demo.js'
3. set TextFiled's variant="filled"

Your Environment 🌎

Tech	Version
Material-UI (core)	v4.6.1
Material-UI (lab)	v4.0.0-alpha.32
React	v16.11.0
OS	macOS 10.13.16
Browsers	chrome 78.0.3904.97, firefox 70.0.1

[oliviertassinari]

Thanks for the report. I'm surprised we didn't get it earlier. What do you think of the icon position with the Select component? We should be able to solve this issue with #18460 at the same time.

[eyalito]

Thanks for the prompt answer.
The icon position of the Select component filled variant is inline with material design specs. It might be more aesthetic to have it centered-aligned with the selected value, once a value is selected. But that's only my aesthetics :)
The Autocomplete filled variant should probably also follow material design specs.