GitLab

- We don't have to use DefaultActivationController because
  wm::FocusController provides activation controls.
- FocusController should be registered as a pre-target handler
  to change the focus on mouse click.
- InitializeInputMethodForTesting seems unnecessary. Text input
  is working well while no actual input methods are available.

BUG=None
R=jamescook@chromium.org, oshima@chromium.org
TEST=manually

Review URL: https://codereview.chromium.org/310463010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274596 0039d316-1c4b-4281-b951-d872f2087c98