ui: Remove some file paths that do not exist anymore.

Looks like with recent refactoring those paths are not necessary
anymore. They are also wrong, so they don't have any effect. Removing it
now. These were discovered in r247866
(https://codereview.chromium.org/147803002)

BUG=299841
TEST=ui_unittests
TBR=tony@chromium.org,ben@chromium.org

Review URL: https://codereview.chromium.org/167843004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251631 0039d316-1c4b-4281-b951-d872f2087c98
Cleanup: Move kChromeDevToolsScheme constant into content namespace.

BUG=None
TEST=None, no functional changes
TBR=jam@chromium.org

Review URL: https://codereview.chromium.org/168953002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251632 0039d316-1c4b-4281-b951-d872f2087c98
Allow --enable-app-list-folder in about:flags in Linux Aura.

BUG=343362

Review URL: https://codereview.chromium.org/165923002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251633 0039d316-1c4b-4281-b951-d872f2087c98