Wenyu Zhang b6d752d52c
[ChipTextField] Use MDCChipTextFieldScrollView to replace leftView functionality for flexibility and extensibility (proof of concept) (#6167)
This PR is dependent on https://github.com/material-components/material-components-ios/pull/6035. And there is no new API change on MDCChipTextField class level.

This PR is meant to solve the problem mentioned in https://github.com/material-components/material-components-ios/pull/6035 -> "Enabling scrolling of the Chips and the remaining alignment issues will be resolved in followup PRs." 
The issues it solves:
(1) Alignment (a way to adjust it also)
(2) clear button
(3) the coupling issue with apple's leftView in the original PR.

Screenshots:
![simulator screen shot - iphone xs - 2019-01-02 at 11 30 50](https://user-images.githubusercontent.com/8836258/50601363-f249be80-0e81-11e9-8afc-515322a22e52.png)
![simulator screen shot - iphone xs - 2019-01-02 at 11 30 54](https://user-images.githubusercontent.com/8836258/50601366-f4138200-0e81-11e9-9869-27d70871a957.png)
![simulator screen shot - iphone xs - 2019-01-02 at 11 30 57](https://user-images.githubusercontent.com/8836258/50601370-f544af00-0e81-11e9-88f1-7da072b1d5b9.png)
2019-01-09 13:28:45 -05:00
..