Resolve namespace scope issue for "switches"

When building using Jumbo files gets merged.
This results in a conflict with the namespace switches in:
chrome/browser/extensions/bookmark_app_helper.cc
chrome/browser/extensions/extension_util.cc

This commit solves this by specifying that the global
namespace should be used, by adding the "::" prefix.

Bug: 850484,856964,860646
Change-Id: I6b7b8343bb66ea5c8a5796f77b85c882085f5d93
Reviewed-on: https://chromium-review.googlesource.com/1127661
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#573000}
2 files changed