Make SmartReplyConstants thread-safe.

    private final int mDefaultMinNumSystemGeneratedReplies;

    private final int mDefaultMaxNumActions;

    private boolean mEnabled;

    private boolean mRequiresTargetingP;

    private int mMaxSqueezeRemeasureAttempts;

    private boolean mEditChoicesBeforeSending;

    private boolean mShowInHeadsUp;

    private int mMinNumSystemGeneratedReplies;

    private int mMaxNumActions;

    // These fields are updated on the UI thread but can be accessed on both the UI thread and

    // background threads. We use the volatile keyword here instead of synchronization blocks since

    // we only care about variable updates here being visible to other threads (and not for example

    // whether the variables we are reading were updated in the same go).

    private volatile boolean mEnabled;

    private volatile boolean mRequiresTargetingP;

    private volatile int mMaxSqueezeRemeasureAttempts;

    private volatile boolean mEditChoicesBeforeSending;

    private volatile boolean mShowInHeadsUp;

    private volatile int mMinNumSystemGeneratedReplies;

    private volatile int mMaxNumActions;

    private final Context mContext;

    private final KeyValueListParser mParser = new KeyValueListParser(',');