Work on getting things built with -Wimplicit-fallthrough. This CL was uploaded by git cl split.

Bug: 177475
R=erg@chromium.org

Change-Id: I13b6ae844b98768aaf35eda5e695993617eccb1f
Reviewed-on: https://chromium-review.googlesource.com/889860Reviewed-by: Elliot Glaysher <erg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532111}

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

@@ -337,6 +337,7 @@ void DesktopWindowTreeHostX11::OnFocusEvent(bool focus_in,
         //    (FocusOut with NotifyNonlinearVirtual)
         // |has_pointer_focus_| should be false before and after this event.
         has_pointer_focus_ = false;
+        break;
       default:
         break;
     }
@@ -2065,7 +2066,7 @@ uint32_t DesktopWindowTreeHostX11::DispatchEvent(
           num_coalesced = ui::CoalescePendingMotionEvents(xev, &last_event);
           if (num_coalesced > 0)
             xev = &last_event;
-          // fallthrough
+          FALLTHROUGH;
         case ui::ET_TOUCH_PRESSED:
         case ui::ET_TOUCH_RELEASED: {
           ui::TouchEvent touchev(xev);