Propogate view from toggle button on ChromePicker
The current view state of the ChromeFields input in ChromePicker is not externally accessible and makes it difficult to tie in with other components.

I suggest adding an onToggleView callback to pass the new "view" state as a parameter back up to its container.
e.g:
`if(this.props.onToggleView){
  this.props.onToggleView('hex');
}`

<img width="1628" alt="propsfortogglebtn" src="https://user-images.githubusercontent.com/22799766/52292238-2ece7580-296c-11e9-803a-317085269058.png">
