The IRS plans to use the FIFO method, and it seems the Coinbase "Cost Basis for Taxes" uses this FIFO method for calculating coin basis for both sales and transfers to your own wallet.
The IRS doesn't exactly "plan" to use FIFO. FIFO is the preferred method of the IRS. However, there is debate as to what methodology you could use (LIFO, HCFO, CCFO, average, etc ) since Bitcoins are property and therefore essentially have no particular rules.
A taxpayer is able to choose specific "lots" they wish to sell when they are selling a stock. The taxpayer must advise the broker as to which lot they wish to sell at the time (or prior to) of the sale. I am not sure if this is something that coinbase offers as of now.