Move tree-related classes that Linux code depends on from views/ to app/

TEST=If it compiles and unit_tests pass, it's ok. Just moving files around.

http://crbug.com/11066

Review URL: http://codereview.chromium.org/115185

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@15982 0039d316-1c4b-4281-b951-d872f2087c98
21 files changed