Cleanup: Update TestObject.h to Chromium style.

- rename to test_object.h
- put in content namespace
- CamelCase for function names.

minimal changes for now.

BUG=342118
TEST=None
R=jochen@chromium.org

Review URL: https://codereview.chromium.org/151543005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250857 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250857