remove CHECK in RemoteRootWindowHostWin::Disconnected

This was triggered by the change to restart in desktop mode when running
with the software compositor. But in general, it's possible for a channel
error to happen before SetTargetSurface which sets the host_. Since the
CHECK isn't accomplishing too much, just remove it.

R=cpu@chromium.org, sky@chromium.org
BUG=315057

Review URL: https://codereview.chromium.org/62853002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233437 0039d316-1c4b-4281-b951-d872f2087c98

ui/aura/remote_root_window_host_win.cc

@@ -150,7 +150,8 @@ void RemoteRootWindowHostWin::Connected(IPC::Sender* host, HWND remote_window) {
 }
 
 void RemoteRootWindowHostWin::Disconnected() {
-  CHECK(host_ != NULL);
+  // Don't CHECK here, Disconnected is called on a channel error which can
+  // happen before we're successfully Connected.
   host_ = NULL;
   remote_window_ = NULL;
 }