A base class to load from Google Play Services on Android. Inspired by this: https://medium.com/google-developers/making-loading-data-on-android-lifecycle-aware-897e12760832#.d7rqcayvb

GoogleApiClientLoader.java

import android.content.Context;
import android.content.Loader;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;

import timber.log.Timber;

public abstract class GoogleApiClientLoader<D> extends Loader<D>
        implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {

    /**
     * Do not call {@link GoogleApiClient#disconnect()} on this object, except from
     * {@link GoogleApiClientLoader} class.
     */
    @NonNull
    public final GoogleApiClient mGoogleApiClient;

    @Nullable
    protected D mData;

    @Nullable
    private ConnectionResult mConnectionResult;

    /**
     * Stores away the application context associated with context.
     * Since Loaders can be used across multiple activities it's dangerous to
     * store the context directly; always use {@link #getContext()} to retrieve
     * the Loader's Context, don't use the constructor argument directly.
     * The Context returned by {@link #getContext} is safe to use across
     * Activity instances.
     *
     * @param context used to retrieve the application context.
     */
    public GoogleApiClientLoader(Context context) {
        super(context);
        mGoogleApiClient = getNewApiClient();
    }

    @Override
    protected final void onStartLoading() {
        if (mData != null) deliverResult(mData);
        if (mGoogleApiClient.isConnected()) {
            startLoadingData(mGoogleApiClient);
            // FIXME: 01/04/16 request data from child class
        } else mGoogleApiClient.connect();
    }

    protected abstract void startLoadingData(@NonNull GoogleApiClient googleApiClient);

    protected final void onResult(D data) {
        mData = data;
        deliverResult(data);
    }

    @Override
    protected final void onForceLoad() {
        if (mData != null) deliverResult(mData);
        if (!mGoogleApiClient.isConnected()) mGoogleApiClient.connect();
    }

    @Override
    public final void onConnected(@Nullable Bundle connectionHint) {
        mConnectionResult = null;
        if (mData != null) deliverResult(mData);
        startLoadingData(mGoogleApiClient);
    }

    @Override
    public final void onConnectionSuspended(int cause) {
        Timber.wtf("onConnectionSuspended(cause=%d)", cause);
        deliverResult(null);
    }

    @Override
    public final void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
        mConnectionResult = connectionResult;
        deliverResult(null);
    }

    protected abstract void onGoogleApiClientDisconnect();

    @Override
    protected final void onReset() {
        if (mGoogleApiClient.isConnected()) {
            onGoogleApiClientDisconnect();
            mGoogleApiClient.disconnect();
        }
    }

    /**
     * @return the connection result if {@link #mGoogleApiClient} connection failed,
     * or null otherwise.
     */
    @Nullable
    public final ConnectionResult getConnectionResult() {
        return mConnectionResult;
    }

    @NonNull
    protected abstract GoogleApiClient getNewApiClient();
}