[jumbo][extensions] Give two kPrefsName unique names

In jumbo builds many cc files compile in the same translation unit
which also means that they share the same anonymous namespace. That
means that constant names need to be unique in the whole build
target even if they are in anonymous namespaces.

A service worker extension just introduced a second kPrefsName into
extensions/browser which broke some (but not all) jumbo build
configurations. This patch renames them both to prevent
confusion (from compiler or human).

TBR=lazyboy@chromium.org,rdevlin.cronin@chromium.org

Bug: 889687
Change-Id: I6d3d44d9941038cc8e2304bc3100c7e681ea18a9
Reviewed-on: https://chromium-review.googlesource.com/c/1314468
Reviewed-by: Daniel Bratell <bratell@opera.com>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#604882}
2 files changed