diff -r 000000000000 -r 6474c204b198 mobile/android/base/background/fxa/SkewHandler.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/background/fxa/SkewHandler.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,111 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.background.fxa;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.HashMap;
+
+import org.mozilla.gecko.background.common.log.Logger;
+import org.mozilla.gecko.sync.net.Resource;
+
+import ch.boye.httpclientandroidlib.Header;
+import ch.boye.httpclientandroidlib.HttpHeaders;
+import ch.boye.httpclientandroidlib.HttpResponse;
+import ch.boye.httpclientandroidlib.impl.cookie.DateParseException;
+import ch.boye.httpclientandroidlib.impl.cookie.DateUtils;
+
+public class SkewHandler {
+  private static final String LOG_TAG = "SkewHandler";
+  protected volatile long skewMillis = 0L;
+  protected final String hostname;
+
+  private static final HashMap<String, SkewHandler> skewHandlers = new HashMap<String, SkewHandler>();
+
+  public static SkewHandler getSkewHandlerForResource(final Resource resource) {
+    return getSkewHandlerForHostname(resource.getHostname());
+  }
+
+  public static SkewHandler getSkewHandlerFromEndpointString(final String url) throws URISyntaxException {
+    if (url == null) {
+      throw new IllegalArgumentException("url must not be null.");
+    }
+    URI u = new URI(url);
+    return getSkewHandlerForHostname(u.getHost());
+  }
+
+  public static synchronized SkewHandler getSkewHandlerForHostname(final String hostname) {
+    SkewHandler handler = skewHandlers.get(hostname);
+    if (handler == null) {
+      handler = new SkewHandler(hostname);
+      skewHandlers.put(hostname, handler);
+    }
+    return handler;
+  }
+
+  public static synchronized void clearSkewHandlers() {
+    skewHandlers.clear();
+  }
+
+  public SkewHandler(final String hostname) {
+    this.hostname = hostname;
+  }
+
+  public boolean updateSkewFromServerMillis(long millis, long now) {
+    skewMillis = millis - now;
+    Logger.debug(LOG_TAG, "Updated skew: " + skewMillis + "ms for hostname " + this.hostname);
+    return true;
+  }
+
+  public boolean updateSkewFromHTTPDateString(String date, long now) {
+    try {
+      final long millis = DateUtils.parseDate(date).getTime();
+      return updateSkewFromServerMillis(millis, now);
+    } catch (DateParseException e) {
+      Logger.warn(LOG_TAG, "Unexpected: invalid Date header from " + this.hostname);
+      return false;
+    }
+  }
+
+  public boolean updateSkewFromDateHeader(Header header, long now) {
+    String date = header.getValue();
+    if (null == date) {
+      Logger.warn(LOG_TAG, "Unexpected: null Date header from " + this.hostname);
+      return false;
+    }
+    return updateSkewFromHTTPDateString(date, now);
+  }
+
+  /**
+   * Update our tracked skew value to account for the local clock differing from
+   * the server's.
+   * 
+   * @param response
+   *          the received HTTP response.
+   * @param now
+   *          the current time in milliseconds.
+   * @return true if the skew value was updated, false otherwise.
+   */
+  public boolean updateSkew(HttpResponse response, long now) {
+    Header header = response.getFirstHeader(HttpHeaders.DATE);
+    if (null == header) {
+      Logger.warn(LOG_TAG, "Unexpected: missing Date header from " + this.hostname);
+      return false;
+    }
+    return updateSkewFromDateHeader(header, now);
+  }
+
+  public long getSkewInMillis() {
+    return skewMillis;
+  }
+
+  public long getSkewInSeconds() {
+    return skewMillis / 1000;
+  }
+
+  public void resetSkew() {
+    skewMillis = 0L;
+  }
+}
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