diff -r 000000000000 -r 6474c204b198 mobile/android/base/tests/testPrefsObserver.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/tests/testPrefsObserver.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,108 @@
+package org.mozilla.gecko.tests;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.mozilla.gecko.Actions;
+
+/**
+ * Basic test to check bounce-back from overscroll.
+ * - Load the page and verify it draws
+ * - Drag page downwards by 100 pixels into overscroll, verify it snaps back.
+ * - Drag page rightwards by 100 pixels into overscroll, verify it snaps back.
+ */
+public class testPrefsObserver extends BaseTest {
+    private static final String PREF_TEST_PREF = "robocop.tests.dummy";
+    private static final int PREF_OBSERVE_REQUEST_ID = 0x7357;
+    private static final long PREF_TIMEOUT = 10000;
+
+    private Actions.RepeatedEventExpecter mExpecter;
+
+    public void setPref(boolean value) throws JSONException {
+        mAsserter.dumpLog("Setting pref");
+
+        JSONObject jsonPref = new JSONObject();
+        jsonPref.put("name", PREF_TEST_PREF);
+        jsonPref.put("type", "bool");
+        jsonPref.put("value", value);
+        mActions.sendGeckoEvent("Preferences:Set", jsonPref.toString());
+    }
+
+    public void waitAndCheckPref(boolean value) throws JSONException {
+        mAsserter.dumpLog("Waiting to check pref");
+
+        JSONObject data = null;
+        int requestId = -1;
+
+        while (requestId != PREF_OBSERVE_REQUEST_ID) {
+            data = new JSONObject(mExpecter.blockForEventData());
+            if (!mExpecter.eventReceived()) {
+                mAsserter.ok(false, "Checking pref is correct value", "Didn't receive pref");
+                return;
+            }
+            requestId = data.getInt("requestId");
+        }
+
+        JSONObject pref = data.getJSONArray("preferences").getJSONObject(0);
+        mAsserter.is(pref.getString("name"), PREF_TEST_PREF, "Pref name is correct");
+        mAsserter.is(pref.getString("type"), "bool", "Pref type is correct");
+        mAsserter.is(pref.getBoolean("value"), value, "Pref value is correct");
+    }
+
+    public void verifyDisconnect() throws JSONException {
+        mAsserter.dumpLog("Checking pref observer is removed");
+
+        JSONObject pref = null;
+        int requestId = -1;
+
+        while (requestId != PREF_OBSERVE_REQUEST_ID) {
+            String data = mExpecter.blockForEventDataWithTimeout(PREF_TIMEOUT);
+            if (data == null) {
+                mAsserter.ok(true, "Verifying pref is unobserved", "Didn't get unobserved pref");
+                return;
+            }
+            pref = new JSONObject(data);
+            requestId = pref.getInt("requestId");
+        }
+
+        mAsserter.ok(false, "Received unobserved pref change", "");
+    }
+
+    public void observePref() throws JSONException {
+        mAsserter.dumpLog("Setting up pref observer");
+
+        // Setup the pref observer
+        mExpecter = mActions.expectGeckoEvent("Preferences:Data");
+        mActions.sendPreferencesObserveEvent(PREF_OBSERVE_REQUEST_ID, new String[] { PREF_TEST_PREF });
+    }
+
+    public void removePrefObserver() {
+        mAsserter.dumpLog("Removing pref observer");
+
+        mActions.sendPreferencesRemoveObserversEvent(PREF_OBSERVE_REQUEST_ID);
+    }
+
+    public void testPrefsObserver() {
+        blockForGeckoReady();
+
+        try {
+            setPref(false);
+            observePref();
+            waitAndCheckPref(false);
+
+            setPref(true);
+            waitAndCheckPref(true);
+
+            removePrefObserver();
+            setPref(false);
+            verifyDisconnect();
+        } catch (Exception ex) {
+            mAsserter.ok(false, "exception in testPrefsObserver", ex.toString());
+        } finally {
+            // Make sure we remove the observer - if it's already removed, this
+            // will do nothing.
+            removePrefObserver();
+        }
+        mExpecter.unregisterListener();
+    }
+}
+