sync: beginnings of MessageLoop based SyncerThread

chrome/browser/sync/engine/polling_constants.cc

Index: chrome/browser/sync/engine/polling_constants.cc
diff --git a/chrome/browser/sync/engine/polling_constants.cc b/chrome/browser/sync/engine/polling_constants.cc
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+++ b/chrome/browser/sync/engine/polling_constants.cc
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+// Copyright (c) 2010 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.
+
+#include "base/basictypes.h"
+#include "chrome/browser/sync/engine/polling_constants.h"
+
+namespace browser_sync {
+
+  // Server can overwrite these values via client commands.
+  // Standard short poll. This is used when XMPP is off.
+  // We use high values here to ensure that failure to receive poll updates from
+  // the server doesn't result in rapid-fire polling from the client due to low
+  // local limits.
+  const int64 kDefaultShortPollIntervalSeconds = 3600 * 8;
+  // Long poll is used when XMPP is on.
+  const int64 kDefaultLongPollIntervalSeconds = 3600 * 12;
+
+  // Maximum interval for exponential backoff.
+  const int64 kMaxBackoffSeconds = 60 * 60 * 4;  // 4 hours.
+
+  // Backoff interval randomization factor.
+  const int kBackoffRandomizationFactor = 2;
+
+}  // namespace browser_sync