GitLab

Added a series of histograms under name
"PhoneHub.TaskCompletion.{MessageType}.Result" to track results of each
type of request messages. "RequestAttempted" is logged when a message
was sent, and "ResponseReceived" is logged when a response has came back

Bug: 1150634
Change-Id: I6e57c2a071536a09c8260d89d1e6dc551a7fe57e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568556
Commit-Queue: Meilin Wang <meilinw@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833976}