Merge "Forward Activity stop signal to attached windows." into pi-dev am: d1366f60

                    ViewRootImpl root = mRoots.get(i);

                    // Client might remove the view by "stopped" event.

                    root.setWindowStopped(stopped);

                    // Recursively forward stopped state to View's attached

                    // to this Window rather than the root application token,

                    // e.g. PopupWindow's.

                    setStoppedState(root.mAttachInfo.mWindowToken, stopped);

                }

            }

        }