--- a/mobile/android/base/java/org/mozilla/gecko/db/SharedBrowserDatabaseProvider.java
+++ b/mobile/android/base/java/org/mozilla/gecko/db/SharedBrowserDatabaseProvider.java
@@ -33,17 +33,17 @@ public abstract class SharedBrowserDatab
 
     private static PerProfileDatabases<BrowserDatabaseHelper> databases;
 
     @Override
     protected PerProfileDatabases<BrowserDatabaseHelper> getDatabases() {
         return databases;
     }
 
-    // Can't mark as @Override. Added in API 11.
+    @Override
     public void shutdown() {
         synchronized (SharedBrowserDatabaseProvider.class) {
             databases.shutdown();
             databases = null;
         }
     }
 
     @Override

--- a/mobile/android/tests/background/junit4/resources/robolectric.properties
+++ b/mobile/android/tests/background/junit4/resources/robolectric.properties
@@ -1,2 +1,3 @@
 sdk=21
 constants=org.mozilla.gecko.BuildConfig
+packageName=org.mozilla.gecko

new file mode 100644
--- /dev/null
+++ b/mobile/android/tests/background/junit4/src/org/mozilla/gecko/background/db/DelegatingTestContentProvider.java
@@ -0,0 +1,87 @@
+package org.mozilla.gecko.background.db;
+
+import android.content.ContentProvider;
+import android.content.ContentProviderOperation;
+import android.content.ContentProviderResult;
+import android.content.ContentValues;
+import android.content.OperationApplicationException;
+import android.database.Cursor;
+import android.net.Uri;
+
+import org.mozilla.gecko.db.BrowserContract;
+
+import java.util.ArrayList;
+
+/**
+ * Wrap a ContentProvider, appending &test=1 to all queries.
+ */
+public class DelegatingTestContentProvider extends ContentProvider {
+    protected final ContentProvider mTargetProvider;
+
+    protected static Uri appendUriParam(Uri uri, String param, String value) {
+        return uri.buildUpon().appendQueryParameter(param, value).build();
+    }
+
+    public DelegatingTestContentProvider(ContentProvider targetProvider) {
+        super();
+        mTargetProvider = targetProvider;
+    }
+
+    private Uri appendTestParam(Uri uri) {
+        try {
+            return appendUriParam(uri, BrowserContract.PARAM_IS_TEST, "1");
+        } catch (Exception e) {
+        }
+
+        return null;
+    }
+
+    @Override
+    public boolean onCreate() {
+        return mTargetProvider.onCreate();
+    }
+
+    @Override
+    public String getType(Uri uri) {
+        return mTargetProvider.getType(uri);
+    }
+
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        return mTargetProvider.delete(appendTestParam(uri), selection, selectionArgs);
+    }
+
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        return mTargetProvider.insert(appendTestParam(uri), values);
+    }
+
+    @Override
+    public int update(Uri uri, ContentValues values, String selection,
+                      String[] selectionArgs) {
+        return mTargetProvider.update(appendTestParam(uri), values,
+                selection, selectionArgs);
+    }
+
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection,
+                        String[] selectionArgs, String sortOrder) {
+        return mTargetProvider.query(appendTestParam(uri), projection, selection,
+                selectionArgs, sortOrder);
+    }
+
+    @Override
+    public ContentProviderResult[] applyBatch(ArrayList<ContentProviderOperation> operations)
+            throws OperationApplicationException {
+        return mTargetProvider.applyBatch(operations);
+    }
+
+    @Override
+    public int bulkInsert(Uri uri, ContentValues[] values) {
+        return mTargetProvider.bulkInsert(appendTestParam(uri), values);
+    }
+
+    public ContentProvider getTargetProvider() {
+        return mTargetProvider;
+    }
+}

new file mode 100644
--- /dev/null
+++ b/mobile/android/tests/background/junit4/src/org/mozilla/gecko/background/db/TestTabsProvider.java
@@ -0,0 +1,249 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+package org.mozilla.gecko.background.db;
+
+import android.content.ContentProviderClient;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.RemoteException;
+
+import org.json.simple.JSONArray;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mozilla.gecko.background.testhelpers.TestRunner;
+import org.mozilla.gecko.db.BrowserContract;
+import org.mozilla.gecko.db.TabsProvider;
+import org.mozilla.gecko.sync.repositories.android.BrowserContractHelpers;
+import org.robolectric.shadows.ShadowContentResolver;
+
+@RunWith(TestRunner.class)
+public class TestTabsProvider {
+    public static final String TEST_CLIENT_GUID = "test guid"; // Real GUIDs never contain spaces.
+    public static final String TEST_CLIENT_NAME = "test client name";
+
+    public static final String CLIENTS_GUID_IS = BrowserContract.Clients.GUID + " = ?";
+    public static final String TABS_CLIENT_GUID_IS = BrowserContract.Tabs.CLIENT_GUID + " = ?";
+
+    protected Tab testTab1;
+    protected Tab testTab2;
+    protected Tab testTab3;
+
+    protected TabsProvider provider;
+
+    @Before
+    public void setUp() {
+        provider = new TabsProvider();
+        provider.onCreate();
+        ShadowContentResolver.registerProvider(BrowserContract.TABS_AUTHORITY, new DelegatingTestContentProvider(provider));
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        provider.shutdown();
+        provider = null;
+    }
+
+    protected ContentProviderClient getClientsClient() {
+        final ShadowContentResolver cr = new ShadowContentResolver();
+        return cr.acquireContentProviderClient(BrowserContractHelpers.CLIENTS_CONTENT_URI);
+    }
+
+    protected ContentProviderClient getTabsClient() {
+        final ShadowContentResolver cr = new ShadowContentResolver();
+        return cr.acquireContentProviderClient(BrowserContractHelpers.TABS_CONTENT_URI);
+    }
+
+    protected int deleteTestClient(final ContentProviderClient clientsClient) throws RemoteException {
+        if (clientsClient == null) {
+            return -1;
+        }
+        return clientsClient.delete(BrowserContractHelpers.CLIENTS_CONTENT_URI, CLIENTS_GUID_IS, new String[] { TEST_CLIENT_GUID });
+    }
+
+    protected int deleteAllTestTabs(final ContentProviderClient tabsClient) throws RemoteException {
+        if (tabsClient == null) {
+            return -1;
+        }
+        return tabsClient.delete(BrowserContractHelpers.TABS_CONTENT_URI, TABS_CLIENT_GUID_IS, new String[]{TEST_CLIENT_GUID});
+    }
+
+    protected void insertTestClient(final ContentProviderClient clientsClient) throws RemoteException {
+        ContentValues cv = new ContentValues();
+        cv.put(BrowserContract.Clients.GUID, TEST_CLIENT_GUID);
+        cv.put(BrowserContract.Clients.NAME, TEST_CLIENT_NAME);
+        clientsClient.insert(BrowserContractHelpers.CLIENTS_CONTENT_URI, cv);
+    }
+
+    @SuppressWarnings("unchecked")
+    protected void insertSomeTestTabs(ContentProviderClient tabsClient) throws RemoteException {
+        final JSONArray history1 = new JSONArray();
+        history1.add("http://test.com/test1.html");
+        testTab1 = new Tab("test title 1", "http://test.com/test1.png", history1, 1000);
+
+        final JSONArray history2 = new JSONArray();
+        history2.add("http://test.com/test2.html#1");
+        history2.add("http://test.com/test2.html#2");
+        history2.add("http://test.com/test2.html#3");
+        testTab2 = new Tab("test title 2", "http://test.com/test2.png", history2, 2000);
+
+        final JSONArray history3 = new JSONArray();
+        history3.add("http://test.com/test3.html#1");
+        history3.add("http://test.com/test3.html#2");
+        testTab3 = new Tab("test title 3", "http://test.com/test3.png", history3, 3000);
+
+        tabsClient.insert(BrowserContractHelpers.TABS_CONTENT_URI, testTab1.toContentValues(TEST_CLIENT_GUID, 0));
+        tabsClient.insert(BrowserContractHelpers.TABS_CONTENT_URI, testTab2.toContentValues(TEST_CLIENT_GUID, 1));
+        tabsClient.insert(BrowserContractHelpers.TABS_CONTENT_URI, testTab3.toContentValues(TEST_CLIENT_GUID, 2));
+    }
+
+    // Sanity.
+    @Test
+    public void testObtainCP() {
+        final ContentProviderClient clientsClient = getClientsClient();
+        Assert.assertNotNull(clientsClient);
+        clientsClient.release();
+
+        final ContentProviderClient tabsClient = getTabsClient();
+        Assert.assertNotNull(tabsClient);
+        tabsClient.release();
+    }
+
+    @Test
+    public void testWipeClients() throws RemoteException {
+        final Uri uri = BrowserContractHelpers.CLIENTS_CONTENT_URI;
+        final ContentProviderClient clientsClient = getClientsClient();
+
+        // Have to ensure that it's empty…
+        clientsClient.delete(uri, null, null);
+
+        int deleted = clientsClient.delete(uri, null, null);
+        Assert.assertEquals(0, deleted);
+    }
+
+    @Test
+    public void testWipeTabs() throws RemoteException {
+        final ContentProviderClient tabsClient = getTabsClient();
+
+        // Have to ensure that it's empty…
+        deleteAllTestTabs(tabsClient);
+
+        int deleted = deleteAllTestTabs(tabsClient);
+        Assert.assertEquals(0, deleted);
+    }
+
+    @Test
+    public void testStoreAndRetrieveClients() throws RemoteException {
+        final Uri uri = BrowserContractHelpers.CLIENTS_CONTENT_URI;
+        final ContentProviderClient clientsClient = getClientsClient();
+
+        // Have to ensure that it's empty…
+        clientsClient.delete(uri, null, null);
+
+        final long now = System.currentTimeMillis();
+        final ContentValues first = new ContentValues();
+        final ContentValues second = new ContentValues();
+        first.put(BrowserContract.Clients.GUID, "abcdefghijkl");
+        first.put(BrowserContract.Clients.NAME, "Frist Psot");
+        first.put(BrowserContract.Clients.LAST_MODIFIED, now + 1);
+        second.put(BrowserContract.Clients.GUID, "mnopqrstuvwx");
+        second.put(BrowserContract.Clients.NAME, "Second!!1!");
+        second.put(BrowserContract.Clients.LAST_MODIFIED, now + 2);
+
+        ContentValues[] values = new ContentValues[] { first, second };
+        final int inserted = clientsClient.bulkInsert(uri, values);
+        Assert.assertEquals(2, inserted);
+
+        final String since = BrowserContract.Clients.LAST_MODIFIED + " >= ?";
+        final String[] nowArg = new String[] { String.valueOf(now) };
+        final String guidAscending = BrowserContract.Clients.GUID + " ASC";
+        Cursor cursor = clientsClient.query(uri, null, since, nowArg, guidAscending);
+
+        Assert.assertNotNull(cursor);
+        try {
+            Assert.assertTrue(cursor.moveToFirst());
+            Assert.assertEquals(2, cursor.getCount());
+
+            final String g1 = cursor.getString(cursor.getColumnIndexOrThrow(BrowserContract.Clients.GUID));
+            final String n1 = cursor.getString(cursor.getColumnIndexOrThrow(BrowserContract.Clients.NAME));
+            final long m1   = cursor.getLong(cursor.getColumnIndexOrThrow(BrowserContract.Clients.LAST_MODIFIED));
+            Assert.assertEquals(first.get(BrowserContract.Clients.GUID), g1);
+            Assert.assertEquals(first.get(BrowserContract.Clients.NAME), n1);
+            Assert.assertEquals(now + 1, m1);
+
+            Assert.assertTrue(cursor.moveToNext());
+            final String g2 = cursor.getString(cursor.getColumnIndexOrThrow(BrowserContract.Clients.GUID));
+            final String n2 = cursor.getString(cursor.getColumnIndexOrThrow(BrowserContract.Clients.NAME));
+            final long m2   = cursor.getLong(cursor.getColumnIndexOrThrow(BrowserContract.Clients.LAST_MODIFIED));
+            Assert.assertEquals(second.get(BrowserContract.Clients.GUID), g2);
+            Assert.assertEquals(second.get(BrowserContract.Clients.NAME), n2);
+            Assert.assertEquals(now + 2, m2);
+
+            Assert.assertFalse(cursor.moveToNext());
+        } finally {
+            cursor.close();
+        }
+
+        int deleted = clientsClient.delete(uri, null, null);
+        Assert.assertEquals(2, deleted);
+    }
+
+    @Test
+    public void testTabFromCursor() throws Exception {
+        final ContentProviderClient tabsClient = getTabsClient();
+        final ContentProviderClient clientsClient = getClientsClient();
+
+        deleteAllTestTabs(tabsClient);
+        deleteTestClient(clientsClient);
+        insertTestClient(clientsClient);
+        insertSomeTestTabs(tabsClient);
+
+        final String positionAscending = BrowserContract.Tabs.POSITION + " ASC";
+        Cursor cursor = null;
+        try {
+            cursor = tabsClient.query(BrowserContractHelpers.TABS_CONTENT_URI, null, TABS_CLIENT_GUID_IS, new String[] { TEST_CLIENT_GUID }, positionAscending);
+            Assert.assertEquals(3, cursor.getCount());
+
+            cursor.moveToFirst();
+            final Tab parsed1 = Tab.fromCursor(cursor);
+            Assert.assertEquals(testTab1, parsed1);
+
+            cursor.moveToNext();
+            final Tab parsed2 = Tab.fromCursor(cursor);
+            Assert.assertEquals(testTab2, parsed2);
+
+            cursor.moveToPosition(2);
+            final Tab parsed3 = Tab.fromCursor(cursor);
+            Assert.assertEquals(testTab3, parsed3);
+        } finally {
+            cursor.close();
+        }
+    }
+
+    @Test
+    public void testDeletingClientDeletesTabs() throws Exception {
+        final ContentProviderClient tabsClient = getTabsClient();
+        final ContentProviderClient clientsClient = getClientsClient();
+
+        deleteAllTestTabs(tabsClient);
+        deleteTestClient(clientsClient);
+        insertTestClient(clientsClient);
+        insertSomeTestTabs(tabsClient);
+
+        // Delete just the client...
+        clientsClient.delete(BrowserContractHelpers.CLIENTS_CONTENT_URI, CLIENTS_GUID_IS, new String [] { TEST_CLIENT_GUID });
+
+        Cursor cursor = null;
+        try {
+            cursor = tabsClient.query(BrowserContractHelpers.TABS_CONTENT_URI, null, TABS_CLIENT_GUID_IS, new String[] { TEST_CLIENT_GUID }, null);
+            // ... and all that client's tabs should be removed.
+            Assert.assertEquals(0, cursor.getCount());
+        } finally {
+            cursor.close();
+        }
+    }
+}