Send page Transaction Fee feedback

[alextsg]

• There may not be enough room to display the prices for different currencies, so I think we're going with a design similar to:
  
  Can we get a mockup with our UI styles?

• If the user clicks "Advanced options" to enter the speed up modal, manually enters in a new gas price, then returns back to the send screen, how do we represent the new custom value in the send screen since it wouldn’t be one of the 3 options?

• If the user enters in a new value via "Advanced options", then decides he wants to go back to one of the pre-set options, how does he do that?

• If there is an error with the API/request and we are unable to retrieve the 3 values for the options, what is the fallback? Show the current design?
  

[cjeria]

Here's a slight enhancement to the gas component and the basic flow/logic.

If there is an error with the API/request and we are unable to retrieve the 3 values for the options, what is the fallback? Show the current design?

Let's fall back to this component. I intentionally omitted the lever icon to be more explicit with copy "Advanced options"

Other thoughts:

• I'm tempted to experiment with putting the gas selection in a second step in the flow gas is becoming an important step in the send flow and we'll be able to use this nicer component.

Thoughts?

[bdresser]

@cjeria let's start with the first option to get this out with minimal changes to what Kyokan already has - then we can think about breaking this out into its own step as the next iteration

[bdresser]

Closing this as part of MetaMask/metamask-extension#4789