Merge "Trigger app transition explicitly when nothing gets resumed" into rvc-dev

            mRootWindowContainer.ensureVisibilityAndConfig(null /* starting */,

                    getDisplay().mDisplayId, false /* markFrozenIfConfigChanged */,

                    false /* deferResume */);

            // Usually resuming a top activity triggers the next app transition, but nothing's got

            // resumed in this case, so we need to execute it explicitly.

            getDisplay().mDisplayContent.executeAppTransition();

        } else {

            mRootWindowContainer.resumeFocusedStacksTopActivities();

        }