Access ChromotingHost::clients_ only on network thread.

Previously ChromotingHost was doing some work on the main thread and
some on the network thread. |clients_| and some other members were
accessed without lock on both of these threads. Moved most of the
ChromotingHost activity to the network thread to avoid possible
race conditions.

BUG=96325
TEST=Chromoting works

Review URL: http://codereview.chromium.org/8495024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@109556 0039d316-1c4b-4281-b951-d872f2087c98
void ClientSession::RecordMouseButtonState(const MouseEvent& event) {
  if (event.has_button() && event.has_button_down()) {
    if (event.button() >= 1 && event.button() < MouseEvent::BUTTON_MAX) {
      uint32 button_change = 1 << (event.button() - 1);
      if (event.button_down()) {
        remote_mouse_button_state_ |= button_change;
      } else {
        remote_mouse_button_state_ &= ~button_change;
      }
    }
  }
}

void ClientSession::RecordMouseButtonState(const MouseEvent& event) {
  if (event.has_button() && event.has_button_down()) {
    if (event.button() >= 1 && event.button() < MouseEvent::BUTTON_MAX) {
      uint32 button_change = 1 << (event.button() - 1);
      if (event.button_down()) {
        remote_mouse_button_state_ |= button_change;
      } else {
        remote_mouse_button_state_ &= ~button_change;
      }
    }
  }
}
