blink: Rename MovableString to ParkableString.

MovableStrings don't have anything to do with std::move(), change their
names to a more meaningful one.

Also fix a couple trivial "git cl lint" warnings.

Bug: 877044
Change-Id: I5a2b500c6161725bdb6b64b48af8554c2d6c260f
Reviewed-on: https://chromium-review.googlesource.com/1194024
Commit-Queue: Benoit L <lizeb@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587527}
24 files changed