Merge \\"Fixed race condition by using a separate counter\\" into nyc-mr1-dev am: d2e8ae4a

import java.util.List;

import java.util.Objects;

import java.util.Set;

import java.util.concurrent.atomic.AtomicInteger;

/**

 * Helper class for {@link ActivityManagerService} responsible for multi-user functionality.

                uss.switching = true;

                mCurWaitingUserSwitchCallbacks = curWaitingUserSwitchCallbacks;

            }

            final AtomicInteger waitingCallbacksCount = new AtomicInteger(observerCount);

            for (int i = 0; i < observerCount; i++) {

                try {

                    // Prepend with unique prefix to guarantee that keys are unique

                                }

                                curWaitingUserSwitchCallbacks.remove(name);

                                // Continue switching if all callbacks have been notified

                                if (curWaitingUserSwitchCallbacks.isEmpty()) {

                                if (waitingCallbacksCount.decrementAndGet() == 0) {

                                    sendContinueUserSwitchLocked(uss, oldUserId, newUserId);

                                }

                            }