Add 2-finger swipe gesture for mouse-wheel in Chromoting Android client.

Since a two-finger gesture is also used for scaling, this adds some code
to disambiguate the two gestures.

R=jamiewalch@chromium.org

Review URL: https://codereview.chromium.org/89553002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237641 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237641
Move Posix file utils to the base namespace.

BUG=
R=rvargas@chromium.org

Review URL: https://codereview.chromium.org/89523002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237642 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237642