Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/omaha/OmahaClient.java

Index: chrome/android/java_staging/src/org/chromium/chrome/browser/omaha/OmahaClient.java
diff --git a/chrome/android/java_staging/src/org/chromium/chrome/browser/omaha/OmahaClient.java b/chrome/android/java_staging/src/org/chromium/chrome/browser/omaha/OmahaClient.java
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index 0000000000000000000000000000000000000000..4d540645ae90d2d202b0bd94ed86dd2fb71f4d3f
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+++ b/chrome/android/java_staging/src/org/chromium/chrome/browser/omaha/OmahaClient.java
@@ -0,0 +1,833 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.omaha;
+
+import android.app.AlarmManager;
+import android.app.IntentService;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.content.pm.ApplicationInfo;
+import android.os.Looper;
+import android.util.Log;
+
+import org.chromium.base.ApiCompatibilityUtils;
+import org.chromium.base.ApplicationStatus;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.SuppressFBWarnings;
+import org.chromium.chrome.browser.ChromeMobileApplication;
+
+import java.io.BufferedOutputStream;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.Map;
+import java.util.UUID;
+
+/**
+ * Keeps tabs on the current state of Chrome, tracking if and when a request should be sent to the
+ * Omaha Server.
+ *
+ * A hook in ChromeActivity's doDeferredResume() initializes the service.  Further attempts to
+ * reschedule events will be scheduled by the class itself.
+ *
+ * Each request to the server will perform an update check and ping the server.
+ * We use a repeating alarm to schedule the XML requests to be generated 5 hours apart.
+ * If Chrome isn't running when the alarm is fired, the request generation will be stalled until
+ * the next time Chrome runs.
+ *
+ * mevissen suggested being conservative with our timers for sending requests.
+ * POST attempts that fail to be acknowledged by the server are re-attempted, with at least
+ * one hour between each attempt.
+ *
+ * Status is saved directly to the the disk after every operation.  Unit tests testing the code
+ * paths without using Intents may need to call restoreState() manually as it is not automatically
+ * handled in onCreate().
+ *
+ * Implementation notes:
+ * http://docs.google.com/a/google.com/document/d/1scTCovqASf5ktkOeVj8wFRkWTCeDYw2LrOBNn05CDB0/edit
+ */
+public class OmahaClient extends IntentService {
+    private static final String TAG = "OmahaClient";
+
+    // Intent actions.
+    private static final String ACTION_INITIALIZE =
+            "org.chromium.chrome.browser.omaha.ACTION_INITIALIZE";
+    private static final String ACTION_REGISTER_REQUEST =
+            "org.chromium.chrome.browser.omaha.ACTION_REGISTER_REQUEST";
+    private static final String ACTION_POST_REQUEST =
+            "org.chromium.chrome.browser.omaha.ACTION_POST_REQUEST";
+
+    // Strings for extras.
+    private static final String EXTRA_FORCE_ACTION = "forceAction";
+
+    // Delays between events.
+    private static final long MS_PER_HOUR = 3600000;
+    private static final long MS_POST_BASE_DELAY = MS_PER_HOUR;
+    private static final long MS_POST_MAX_DELAY = 5 * MS_PER_HOUR;
+    private static final long MS_BETWEEN_REQUESTS = 5 * MS_PER_HOUR;
+    private static final int MS_CONNECTION_TIMEOUT = 60000;
+
+    // Flags for retrieving the OmahaClient's state after it's written to disk.
+    // The PREF_PACKAGE doesn't match the current OmahaClient package for historical reasons.
+    @VisibleForTesting
+    static final String PREF_PACKAGE = "com.google.android.apps.chrome.omaha";
+    @VisibleForTesting
+    static final String PREF_PERSISTED_REQUEST_ID = "persistedRequestID";
+    @VisibleForTesting
+    static final String PREF_TIMESTAMP_OF_REQUEST = "timestampOfRequest";
+    @VisibleForTesting
+    static final String PREF_INSTALL_SOURCE = "installSource";
+    private static final String PREF_SEND_INSTALL_EVENT = "sendInstallEvent";
+    private static final String PREF_TIMESTAMP_OF_INSTALL = "timestampOfInstall";
+    private static final String PREF_TIMESTAMP_FOR_NEXT_POST_ATTEMPT =
+            "timestampForNextPostAttempt";
+    private static final String PREF_TIMESTAMP_FOR_NEW_REQUEST = "timestampForNewRequest";
+
+    // Strings indicating how the Chrome APK arrived on the user's device. These values MUST NOT
+    // be changed without updating the corresponding Omaha server strings.
+    static final String INSTALL_SOURCE_SYSTEM = "system_image";
+    static final String INSTALL_SOURCE_ORGANIC = "organic";
+
+    // Lock object used to synchronize all calls that modify or read sIsFreshInstallOrDataCleared.
+    private static final Object sIsFreshInstallLock = new Object();
+
+    @VisibleForTesting
+    static final String PREF_LATEST_VERSION = "latestVersion";
+    @VisibleForTesting
+    static final String PREF_MARKET_URL = "marketURL";
+
+    private static final long INVALID_TIMESTAMP = -1;
+    @VisibleForTesting
+    static final String INVALID_REQUEST_ID = "invalid";
+
+    // Static fields
+    private static boolean sEnableCommunication = true;
+    private static boolean sEnableUpdateDetection = true;
+    private static VersionNumberGetter sVersionNumberGetter = null;
+    private static MarketURLGetter sMarketURLGetter = null;
+    private static Boolean sIsFreshInstallOrDataCleared = null;
+
+    // Member fields not persisted to disk.
+    private boolean mStateHasBeenRestored;
+    private Context mApplicationContext;
+    private ExponentialBackoffScheduler mBackoffScheduler;
+    private RequestGenerator mGenerator;
+
+    // State saved written to and read from disk.
+    private RequestData mCurrentRequest;
+    private long mTimestampOfInstall;
+    private long mTimestampForNextPostAttempt;
+    private long mTimestampForNewRequest;
+    private String mLatestVersion;
+    private String mMarketURL;
+    private String mInstallSource;
+    protected boolean mSendInstallEvent;
+
+    public OmahaClient() {
+        super(TAG);
+        setIntentRedelivery(true);
+    }
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        mApplicationContext = getApplicationContext();
+        mBackoffScheduler = createBackoffScheduler(PREF_PACKAGE, mApplicationContext,
+                MS_POST_BASE_DELAY, MS_POST_MAX_DELAY);
+        mGenerator = createRequestGenerator(mApplicationContext);
+    }
+
+    /**
+     * Sets whether Chrome should be communicating with the Omaha server.
+     * The alternative to using a static field within OmahaClient is using a member variable in
+     * the ChromeTabbedActivity.  The problem is that it is difficult to set the variable before
+     * ChromeTabbedActivity is started.
+     */
+    @VisibleForTesting
+    public static void setEnableCommunication(boolean state) {
+        sEnableCommunication = state;
+    }
+
+    /**
+     * If false, OmahaClient will never report that a newer version is available.
+     */
+    @VisibleForTesting
+    public static void setEnableUpdateDetection(boolean state) {
+        sEnableUpdateDetection = state;
+    }
+
+    @VisibleForTesting
+    long getTimestampForNextPostAttempt() {
+        return mTimestampForNextPostAttempt;
+    }
+
+    @VisibleForTesting
+    long getTimestampForNewRequest() {
+        return mTimestampForNewRequest;
+    }
+
+    @VisibleForTesting
+    int getCumulativeFailedAttempts() {
+        return mBackoffScheduler.getNumFailedAttempts();
+    }
+
+    /**
+     * Creates the scheduler used to space out POST attempts.
+     */
+    @VisibleForTesting
+    ExponentialBackoffScheduler createBackoffScheduler(String prefPackage, Context context,
+            long base, long max) {
+        return new ExponentialBackoffScheduler(prefPackage, context, base, max);
+    }
+
+    /**
+     * Creates the request generator used to create Omaha XML.
+     */
+    @VisibleForTesting
+    RequestGenerator createRequestGenerator(Context context) {
+        return ((ChromeMobileApplication) getApplicationContext()).createOmahaRequestGenerator();
+    }
+
+    /**
+     * Handles an action on a thread separate from the UI thread.
+     * @param intent Intent fired by some part of Chrome.
+     */
+    @Override
+    public void onHandleIntent(Intent intent) {
+        assert Looper.myLooper() != Looper.getMainLooper();
+
+        if (!sEnableCommunication) {
+            Log.v(TAG, "Disabled.  Ignoring intent.");
+            return;
+        }
+
+        if (mGenerator == null) {
+            Log.e(TAG, "No request generator set.  Ignoring intent.");
+            return;
+        }
+
+        if (!mStateHasBeenRestored) {
+            restoreState();
+        }
+
+        if (ACTION_INITIALIZE.equals(intent.getAction())) {
+            handleInitialize();
+        } else if (ACTION_REGISTER_REQUEST.equals(intent.getAction())) {
+            handleRegisterRequest(intent);
+        } else if (ACTION_POST_REQUEST.equals(intent.getAction())) {
+            handlePostRequestIntent(intent);
+        } else {
+            Log.e(TAG, "Got unknown action from intent: " + intent.getAction());
+        }
+    }
+
+    public static Intent createInitializeIntent(Context context) {
+        Intent intent = new Intent(context, OmahaClient.class);
+        intent.setAction(ACTION_INITIALIZE);
+        return intent;
+    }
+
+    /**
+     * Start a recurring alarm to fire request generation intents.
+     */
+    private void handleInitialize() {
+        scheduleRepeatingAlarm();
+
+        // If a request exists, fire a POST intent to restart its timer.
+        if (hasRequest()) {
+            Intent postIntent = createPostRequestIntent(mApplicationContext, false);
+            startService(postIntent);
+        }
+    }
+
+    public static Intent createRegisterRequestIntent(Context context, boolean force) {
+        Intent intent = new Intent(context, OmahaClient.class);
+        intent.setAction(ACTION_REGISTER_REQUEST);
+        intent.putExtra(EXTRA_FORCE_ACTION, force);
+        return intent;
+    }
+
+    /**
+     * Determines if a new request should be generated.  New requests are only generated if enough
+     * time has passed between now and the last time a request was generated.
+     */
+    private void handleRegisterRequest(Intent intent) {
+        boolean force = intent.getBooleanExtra(EXTRA_FORCE_ACTION, false);
+        if (!isChromeBeingUsed() && !force) {
+            cancelRepeatingAlarm();
+            return;
+        }
+
+        // If the current request is too old, generate a new one.
+        long currentTimestamp = mBackoffScheduler.getCurrentTime();
+        boolean isTooOld = hasRequest()
+                && mCurrentRequest.getAgeInMilliseconds(currentTimestamp) >= MS_BETWEEN_REQUESTS;
+        boolean isOverdue = !hasRequest() && currentTimestamp >= mTimestampForNewRequest;
+        if (isTooOld || isOverdue || force) {
+            registerNewRequest(currentTimestamp);
+        }
+
+        // Create an intent to send the request.  If we're forcing a registration, force the POST,
+        // as well.
+        if (hasRequest()) {
+            Intent postIntent = createPostRequestIntent(mApplicationContext, force);
+            startService(postIntent);
+        }
+    }
+
+    public static Intent createPostRequestIntent(Context context, boolean force) {
+        Intent intent = new Intent(context, OmahaClient.class);
+        intent.setAction(ACTION_POST_REQUEST);
+        intent.putExtra(EXTRA_FORCE_ACTION, force);
+        return intent;
+    }
+
+    /**
+     * Sends the request it is holding.
+     */
+    @VisibleForTesting
+    private void handlePostRequestIntent(Intent intent) {
+        if (!hasRequest()) {
+            return;
+        }
+
+        boolean force = intent.getBooleanExtra(EXTRA_FORCE_ACTION, false);
+
+        // If enough time has passed since the last attempt, try sending a request.
+        long currentTimestamp = mBackoffScheduler.getCurrentTime();
+        if (currentTimestamp >= mTimestampForNextPostAttempt || force) {
+            // All requests made during the same session should have the same ID.
+            String sessionID = generateRandomUUID();
+            boolean sendingInstallRequest = mSendInstallEvent;
+            boolean succeeded = generateAndPostRequest(currentTimestamp, sessionID);
+
+            if (succeeded && sendingInstallRequest) {
+                // Only the first request ever generated should contain an install event.
+                mSendInstallEvent = false;
+
+                // Create and immediately send another request for a ping and update check.
+                registerNewRequest(currentTimestamp);
+                succeeded = generateAndPostRequest(currentTimestamp, sessionID);
+            }
+
+            if (force) {
+                if (succeeded) {
+                    Log.v(TAG, "Requests successfully sent to Omaha server.");
+                } else {
+                    Log.e(TAG, "Requests failed to reach Omaha server.");
+                }
+            }
+        } else {
+            // Set an alarm to POST at the proper time.  Previous alarms are destroyed.
+            Intent postIntent = createPostRequestIntent(mApplicationContext, false);
+            mBackoffScheduler.createAlarm(postIntent, mTimestampForNextPostAttempt);
+        }
+
+        // Write everything back out again to save our state.
+        saveState();
+    }
+
+    private boolean generateAndPostRequest(long currentTimestamp, String sessionID) {
+        try {
+            // Generate the XML for the current request.
+            long installAgeInDays = RequestGenerator.installAge(currentTimestamp,
+                    mTimestampOfInstall, mCurrentRequest.isSendInstallEvent());
+            String version = getVersionNumberGetter().getCurrentlyUsedVersion(mApplicationContext);
+            String xml =
+                    mGenerator.generateXML(sessionID, version, installAgeInDays, mCurrentRequest);
+
+            // Send the request to the server & wait for a response.
+            String response = postRequest(currentTimestamp, xml);
+            parseServerResponse(response);
+
+            // If we've gotten this far, we've successfully sent a request.
+            mCurrentRequest = null;
+            mTimestampForNextPostAttempt = currentTimestamp + MS_POST_BASE_DELAY;
+            mBackoffScheduler.resetFailedAttempts();
+            Log.i(TAG, "Request to Server Successful. Timestamp for next request:"
+                    + String.valueOf(mTimestampForNextPostAttempt));
+
+            return true;
+        } catch (RequestFailureException e) {
+            // Set the alarm to try again later.
+            Log.e(TAG, "Failed to contact server: ", e);
+            Intent postIntent = createPostRequestIntent(mApplicationContext, false);
+            mTimestampForNextPostAttempt = mBackoffScheduler.createAlarm(postIntent);
+            mBackoffScheduler.increaseFailedAttempts();
+            return false;
+        }
+    }
+
+    /**
+     * Sets a repeating alarm that fires request registration Intents.
+     * Setting the alarm overwrites whatever alarm is already there, and rebooting
+     * clears whatever alarms are currently set.
+     */
+    private void scheduleRepeatingAlarm() {
+        Intent registerIntent = createRegisterRequestIntent(mApplicationContext, false);
+        PendingIntent pIntent =
+                PendingIntent.getService(mApplicationContext, 0, registerIntent, 0);
+        AlarmManager am =
+                (AlarmManager) mApplicationContext.getSystemService(Context.ALARM_SERVICE);
+        setAlarm(am, pIntent, AlarmManager.RTC, mTimestampForNewRequest);
+    }
+
+    /**
+     * Sets up a timer to fire after each interval.
+     * Override to prevent a real alarm from being set.
+     */
+    @VisibleForTesting
+    protected void setAlarm(AlarmManager am, PendingIntent operation, int alarmType,
+            long triggerAtTime) {
+        am.setRepeating(AlarmManager.RTC, triggerAtTime, MS_BETWEEN_REQUESTS, operation);
+    }
+
+    /**
+     * Cancels the alarm that launches this service.  It will be replaced when Chrome next resumes.
+     */
+    private void cancelRepeatingAlarm() {
+        Intent requestIntent = createRegisterRequestIntent(mApplicationContext, false);
+        PendingIntent pendingIntent = PendingIntent.getService(mApplicationContext, 0,
+                requestIntent, PendingIntent.FLAG_NO_CREATE);
+        // Setting FLAG_NO_CREATE forces Android to return an already existing PendingIntent.
+        // Here it would be the one that was used to create the existing alarm (if it exists).
+        // If the pendingIntent is null, it is likely that no alarm was created.
+        if (pendingIntent != null) {
+            AlarmManager am =
+                    (AlarmManager) mApplicationContext.getSystemService(Context.ALARM_SERVICE);
+            am.cancel(pendingIntent);
+            pendingIntent.cancel();
+        }
+    }
+
+    /**
+     * Determine whether or not Chrome is currently being used actively.
+     */
+    @VisibleForTesting
+    protected boolean isChromeBeingUsed() {
+        boolean isChromeVisible = ApplicationStatus.hasVisibleActivities();
+        boolean isScreenOn = ApiCompatibilityUtils.isInteractive(mApplicationContext);
+        return isChromeVisible && isScreenOn;
+    }
+
+    /**
+     * Registers a new request with the current timestamp.  Internal timestamps are reset to start
+     * fresh.
+     * @param currentTimestamp Current time.
+     */
+    @VisibleForTesting
+    void registerNewRequest(long currentTimestamp) {
+        mCurrentRequest = createRequestData(currentTimestamp, null);
+        mBackoffScheduler.resetFailedAttempts();
+        mTimestampForNextPostAttempt = currentTimestamp;
+
+        // Tentatively set the timestamp for a new request.  This will be updated when the server
+        // is successfully contacted.
+        mTimestampForNewRequest = currentTimestamp + MS_BETWEEN_REQUESTS;
+        scheduleRepeatingAlarm();
+
+        saveState();
+    }
+
+    private RequestData createRequestData(long currentTimestamp, String persistedID) {
+        // If we're sending a persisted event, keep trying to send the same request ID.
+        String requestID;
+        if (persistedID == null || INVALID_REQUEST_ID.equals(persistedID)) {
+            requestID = generateRandomUUID();
+        } else {
+            requestID = persistedID;
+        }
+        return new RequestData(mSendInstallEvent, currentTimestamp, requestID, mInstallSource);
+    }
+
+    @VisibleForTesting
+    boolean hasRequest() {
+        return mCurrentRequest != null;
+    }
+
+    /**
+     * Posts the request to the Omaha server.
+     * @return the XML response as a String.
+     * @throws RequestFailureException if the request fails.
+     */
+    @VisibleForTesting
+    String postRequest(long timestamp, String xml) throws RequestFailureException {
+        String response = null;
+
+        HttpURLConnection urlConnection = null;
+        try {
+            urlConnection = createConnection();
+            setUpPostRequest(timestamp, urlConnection, xml);
+            sendRequestToServer(urlConnection, xml);
+            response = readResponseFromServer(urlConnection);
+        } finally {
+            if (urlConnection != null) {
+                urlConnection.disconnect();
+            }
+        }
+
+        return response;
+    }
+
+    /**
+     * Parse the server's response and confirm that we received an OK response.
+     */
+    private void parseServerResponse(String response) throws RequestFailureException {
+        String appId = mGenerator.getAppId();
+        boolean sentPingAndUpdate = !mSendInstallEvent;
+        ResponseParser parser =
+                new ResponseParser(appId, mSendInstallEvent, sentPingAndUpdate, sentPingAndUpdate);
+        parser.parseResponse(response);
+        mTimestampForNewRequest = mBackoffScheduler.getCurrentTime() + MS_BETWEEN_REQUESTS;
+        mLatestVersion = parser.getNewVersion();
+        mMarketURL = parser.getURL();
+        scheduleRepeatingAlarm();
+    }
+
+    /**
+     * Returns a HttpURLConnection to the server.
+     */
+    @VisibleForTesting
+    protected HttpURLConnection createConnection() throws RequestFailureException {
+        try {
+            URL url = new URL(mGenerator.getServerUrl());
+            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+            connection.setConnectTimeout(MS_CONNECTION_TIMEOUT);
+            connection.setReadTimeout(MS_CONNECTION_TIMEOUT);
+            return connection;
+        } catch (MalformedURLException e) {
+            throw new RequestFailureException("Caught a malformed URL exception.", e);
+        } catch (IOException e) {
+            throw new RequestFailureException("Failed to open connection to URL", e);
+        }
+    }
+
+    /**
+     * Prepares the HTTP header.
+     */
+    private void setUpPostRequest(long timestamp, HttpURLConnection urlConnection, String xml)
+            throws RequestFailureException {
+        try {
+            urlConnection.setDoOutput(true);
+            urlConnection.setFixedLengthStreamingMode(xml.getBytes().length);
+            if (mSendInstallEvent && getCumulativeFailedAttempts() > 0) {
+                String age = Long.toString(mCurrentRequest.getAgeInSeconds(timestamp));
+                urlConnection.addRequestProperty("X-RequestAge", age);
+            }
+        } catch (IllegalAccessError e) {
+            throw new RequestFailureException("Caught an IllegalAccessError:", e);
+        } catch (IllegalArgumentException e) {
+            throw new RequestFailureException("Caught an IllegalArgumentException:", e);
+        } catch (IllegalStateException e) {
+            throw new RequestFailureException("Caught an IllegalStateException:", e);
+        }
+    }
+
+    /**
+     * Sends the request to the server.
+     */
+    private void sendRequestToServer(HttpURLConnection urlConnection, String xml)
+            throws RequestFailureException {
+        try {
+            OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
+            OutputStreamWriter writer = new OutputStreamWriter(out);
+            writer.write(xml, 0, xml.length());
+            writer.close();
+            checkServerResponseCode(urlConnection);
+        } catch (IOException e) {
+            throw new RequestFailureException("Failed to write request to server: ", e);
+        }
+    }
+
+    /**
+     * Reads the response from the Omaha Server.
+     */
+    private String readResponseFromServer(HttpURLConnection urlConnection)
+            throws RequestFailureException {
+        try {
+            InputStreamReader reader = new InputStreamReader(urlConnection.getInputStream());
+            BufferedReader in = new BufferedReader(reader);
+            try {
+                StringBuilder response = new StringBuilder();
+                for (String line = in.readLine(); line != null; line = in.readLine()) {
+                    response.append(line);
+                }
+                checkServerResponseCode(urlConnection);
+                return response.toString();
+            } finally {
+                in.close();
+            }
+        } catch (IOException e) {
+            throw new RequestFailureException("Failed when reading response from server: ", e);
+        }
+    }
+
+    /**
+     * Confirms that the Omaha server sent back an "OK" code.
+     */
+    private void checkServerResponseCode(HttpURLConnection urlConnection)
+            throws RequestFailureException {
+        try {
+            if (urlConnection.getResponseCode() != 200) {
+                throw new RequestFailureException(
+                        "Received " + urlConnection.getResponseCode()
+                        + " code instead of 200 (OK) from the server.  Aborting.");
+            }
+        } catch (IOException e) {
+            throw new RequestFailureException("Failed to read response code from server: ", e);
+        }
+    }
+
+    /**
+     * Checks if we know about a newer version available than the one we're using.  This does not
+     * actually fire any requests over to the server; it just checks the version we stored the last
+     * time we talked to the Omaha server.
+     *
+     * NOTE: This function incurs I/O, so don't use it on the main thread.
+     */
+    public static boolean isNewerVersionAvailable(Context applicationContext) {
+        assert Looper.myLooper() != Looper.getMainLooper();
+
+        // This may be explicitly enabled for some channels and for unit tests.
+        if (!sEnableUpdateDetection) {
+            return false;
+        }
+
+        // If the market link is bad, don't show an update to avoid frustrating users trying to
+        // hit the "Update" button.
+        if ("".equals(getMarketURL(applicationContext))) {
+            return false;
+        }
+
+        // Compare version numbers.
+        VersionNumberGetter getter = getVersionNumberGetter();
+        String currentStr = getter.getCurrentlyUsedVersion(applicationContext);
+        String latestStr =
+                getter.getLatestKnownVersion(applicationContext, PREF_PACKAGE, PREF_LATEST_VERSION);
+
+        VersionNumber currentVersionNumber = VersionNumber.fromString(currentStr);
+        VersionNumber latestVersionNumber = VersionNumber.fromString(latestStr);
+
+        if (currentVersionNumber == null || latestVersionNumber == null) {
+            return false;
+        }
+
+        return currentVersionNumber.isSmallerThan(latestVersionNumber);
+    }
+
+    /**
+     * Determine how the Chrome APK arrived on the device.
+     * @param context Context to pull resources from.
+     * @return A String indicating the install source.
+     */
+    String determineInstallSource(Context context) {
+        boolean isInSystemImage = (getApplicationFlags() & ApplicationInfo.FLAG_SYSTEM) != 0;
+        return isInSystemImage ? INSTALL_SOURCE_SYSTEM : INSTALL_SOURCE_ORGANIC;
+    }
+
+    /**
+     * Returns the Application's flags, used to determine if Chrome was installed as part of the
+     * system image.
+     * @return The Application's flags.
+     */
+    @VisibleForTesting
+    public int getApplicationFlags() {
+        return mApplicationContext.getApplicationInfo().flags;
+    }
+
+    /**
+     * Reads the data back from the file it was saved to.  Uses SharedPreferences to handle I/O.
+     * Sanity checks are performed on the timestamps to guard against clock changing.
+     */
+    @VisibleForTesting
+    void restoreState() {
+        boolean mustRewriteState = false;
+        SharedPreferences preferences =
+                mApplicationContext.getSharedPreferences(PREF_PACKAGE, Context.MODE_PRIVATE);
+        Map<String, ?> items = preferences.getAll();
+
+        // Read out the recorded data.
+        long currentTime = mBackoffScheduler.getCurrentTime();
+        mTimestampForNewRequest =
+                getLongFromMap(items, PREF_TIMESTAMP_FOR_NEW_REQUEST, currentTime);
+        mTimestampForNextPostAttempt =
+                getLongFromMap(items, PREF_TIMESTAMP_FOR_NEXT_POST_ATTEMPT, currentTime);
+
+        long requestTimestamp = getLongFromMap(items, PREF_TIMESTAMP_OF_REQUEST, INVALID_TIMESTAMP);
+
+        // If the preference doesn't exist, it's likely that we haven't sent an install event.
+        mSendInstallEvent = getBooleanFromMap(items, PREF_SEND_INSTALL_EVENT, true);
+
+        // Restore the install source.
+        String defaultInstallSource = determineInstallSource(mApplicationContext);
+        mInstallSource = getStringFromMap(items, PREF_INSTALL_SOURCE, defaultInstallSource);
+
+        // If we're not sending an install event, don't bother restoring the request ID:
+        // the server does not expect to have persisted request IDs for pings or update checks.
+        String persistedRequestId = mSendInstallEvent
+                ? getStringFromMap(items, PREF_PERSISTED_REQUEST_ID, INVALID_REQUEST_ID)
+                : INVALID_REQUEST_ID;
+
+        mCurrentRequest = requestTimestamp == INVALID_TIMESTAMP
+                ? null : createRequestData(requestTimestamp, persistedRequestId);
+
+        mLatestVersion = getStringFromMap(items, PREF_LATEST_VERSION, "");
+        mMarketURL = getStringFromMap(items, PREF_MARKET_URL, "");
+
+        // If we don't have a timestamp for when we installed Chrome, then set it to now.
+        mTimestampOfInstall = getLongFromMap(items, PREF_TIMESTAMP_OF_INSTALL, currentTime);
+
+        // Confirm that the timestamp for the next request is less than the base delay.
+        long delayToNewRequest = mTimestampForNewRequest - currentTime;
+        if (delayToNewRequest > MS_BETWEEN_REQUESTS) {
+            Log.w(TAG, "Delay to next request (" + delayToNewRequest
+                    + ") is longer than expected.  Resetting to now.");
+            mTimestampForNewRequest = currentTime;
+            mustRewriteState = true;
+        }
+
+        // Confirm that the timestamp for the next POST is less than the current delay.
+        long delayToNextPost = mTimestampForNextPostAttempt - currentTime;
+        if (delayToNextPost > mBackoffScheduler.getGeneratedDelay()) {
+            Log.w(TAG, "Delay to next post attempt (" + delayToNextPost
+                    + ") is greater than expected (" + mBackoffScheduler.getGeneratedDelay()
+                    + ").  Resetting to now.");
+            mTimestampForNextPostAttempt = currentTime;
+            mustRewriteState = true;
+        }
+
+        if (mustRewriteState) {
+            saveState();
+        }
+
+        mStateHasBeenRestored = true;
+    }
+
+    /**
+     * Writes out the current state to a file.
+     */
+    private void saveState() {
+        SharedPreferences prefs =
+                mApplicationContext.getSharedPreferences(PREF_PACKAGE, Context.MODE_PRIVATE);
+        SharedPreferences.Editor editor = prefs.edit();
+        editor.putBoolean(PREF_SEND_INSTALL_EVENT, mSendInstallEvent);
+        setIsFreshInstallOrDataHasBeenCleared(mApplicationContext);
+        editor.putLong(PREF_TIMESTAMP_OF_INSTALL, mTimestampOfInstall);
+        editor.putLong(PREF_TIMESTAMP_FOR_NEXT_POST_ATTEMPT, mTimestampForNextPostAttempt);
+        editor.putLong(PREF_TIMESTAMP_FOR_NEW_REQUEST, mTimestampForNewRequest);
+        editor.putLong(PREF_TIMESTAMP_OF_REQUEST,
+                hasRequest() ? mCurrentRequest.getCreationTimestamp() : INVALID_TIMESTAMP);
+        editor.putString(PREF_PERSISTED_REQUEST_ID,
+                hasRequest() ? mCurrentRequest.getRequestID() : INVALID_REQUEST_ID);
+        editor.putString(PREF_LATEST_VERSION, mLatestVersion == null ? "" : mLatestVersion);
+        editor.putString(PREF_MARKET_URL, mMarketURL == null ? "" : mMarketURL);
+
+        if (mInstallSource != null) editor.putString(PREF_INSTALL_SOURCE, mInstallSource);
+
+        editor.apply();
+    }
+
+    /**
+     * Generates a random UUID.
+     */
+    @VisibleForTesting
+    protected String generateRandomUUID() {
+        return UUID.randomUUID().toString();
+    }
+
+    /**
+     * Sets the VersionNumberGetter used to get version numbers.  Set a new one to override what
+     * version numbers are returned.
+     */
+    @VisibleForTesting
+    static void setVersionNumberGetterForTests(VersionNumberGetter getter) {
+        sVersionNumberGetter = getter;
+    }
+
+    @SuppressFBWarnings("LI_LAZY_INIT_STATIC")
+    @VisibleForTesting
+    static VersionNumberGetter getVersionNumberGetter() {
+        if (sVersionNumberGetter == null) {
+            sVersionNumberGetter = new VersionNumberGetter();
+        }
+        return sVersionNumberGetter;
+    }
+
+    /**
+     * Sets the MarketURLGetter used to get version numbers.  Set a new one to override what
+     * URL is returned.
+     */
+    @VisibleForTesting
+    static void setMarketURLGetterForTests(MarketURLGetter getter) {
+        sMarketURLGetter = getter;
+    }
+
+    /**
+     * Returns the stub used to grab the market URL for Chrome.
+     */
+    @SuppressFBWarnings("LI_LAZY_INIT_STATIC")
+    public static String getMarketURL(Context context) {
+        if (sMarketURLGetter == null) {
+            sMarketURLGetter = new MarketURLGetter();
+        }
+        return sMarketURLGetter.getMarketURL(context, PREF_PACKAGE, PREF_MARKET_URL);
+    }
+
+    /**
+     * Pulls a long from the shared preferences map.
+     */
+    private static long getLongFromMap(final Map<String, ?> items, String key, long defaultValue) {
+        Long value = (Long) items.get(key);
+        return value != null ? value : defaultValue;
+    }
+
+    /**
+     * Pulls a string from the shared preferences map.
+     */
+    private static String getStringFromMap(final Map<String, ?> items, String key,
+            String defaultValue) {
+        String value = (String) items.get(key);
+        return value != null ? value : defaultValue;
+    }
+
+    /**
+     * Pulls a boolean from the shared preferences map.
+     */
+    private static boolean getBooleanFromMap(final Map<String, ?> items, String key,
+            boolean defaultValue) {
+        Boolean value = (Boolean) items.get(key);
+        return value != null ? value : defaultValue;
+    }
+
+    /**
+     * @return Whether it is either a fresh install or data has been cleared.
+     * PREF_TIMESTAMP_OF_INSTALL is set within the first few seconds after a fresh install.
+     * sIsFreshInstallOrDataCleared will be set to true if PREF_TIMESTAMP_OF_INSTALL has not
+     * been previously set. Else, it will be set to false. sIsFreshInstallOrDataCleared is
+     * guarded by sLock.
+     * @param applicationContext The current application Context.
+     */
+    public static boolean isFreshInstallOrDataHasBeenCleared(Context applicationContext) {
+        return setIsFreshInstallOrDataHasBeenCleared(applicationContext);
+    }
+
+    private static boolean setIsFreshInstallOrDataHasBeenCleared(Context applicationContext) {
+        synchronized (sIsFreshInstallLock) {
+            if (sIsFreshInstallOrDataCleared == null) {
+                SharedPreferences prefs = applicationContext.getSharedPreferences(
+                        PREF_PACKAGE, Context.MODE_PRIVATE);
+                sIsFreshInstallOrDataCleared = (prefs.getLong(PREF_TIMESTAMP_OF_INSTALL, -1) == -1);
+            }
+            return sIsFreshInstallOrDataCleared;
+        }
+    }
+}