Handful of related instant changes:

chrome/browser/instant/promo_counter.h

Index: chrome/browser/instant/promo_counter.h
diff --git a/chrome/browser/instant/promo_counter.h b/chrome/browser/instant/promo_counter.h
new file mode 100644
index 0000000000000000000000000000000000000000..480f67714f3a6cf4b7d3c4faf588df04349203a5
--- /dev/null
+++ b/chrome/browser/instant/promo_counter.h
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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.
+
+#ifndef CHROME_BROWSER_INSTANT_PROMO_COUNTER_H_
+#define CHROME_BROWSER_INSTANT_PROMO_COUNTER_H_
+#pragma once
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/time.h"
+
+class PrefService;
+class Profile;
+
+// PromoCounter is used to track whether a promo should be shown. The promo is
+// shown for a specified number of days or sessions (launches of chrome).
+class PromoCounter {
+ public:
+  // Creates a new PromoCounter. |pref_key| is used to store prefs related to
+  // the promo. |histogram_key| is the key used to store histograms related to
+  // the promo. See the .cc file for the exact prefs and histogram values used.
+  // |ShouldShow| returns true until the users restarts chrome |max_sessions| or
+  // runs Chrome for |max_days|, or |Hide| is invoked.
+  PromoCounter(Profile* profile,
+               const std::string& pref_key,
+               const std::string& histogram_key,
+               int max_sessions,
+               int max_days);
+  ~PromoCounter();
+
+  // Registers the preferences used by PromoCounter.
+  static void RegisterUserPrefs(PrefService* prefs,
+                                const std::string& base_key);
+
+  // Returns true if the promo should be shown.
+  bool ShouldShow(base::Time current_time);
+
+  // Permanently hides the promo.
+  void Hide();
+
+ private:
+  // Called the first time ShouldShow is invoked. Updates the necessary pref
+  // state and show_.
+  void Init(base::Time current_time);
+
+  // Invoked if the max number of sessions has been encountered.
+  void MaxSessionsEncountered(base::Time current_time);
+
+  // Invoked if the max number of days has elapsed.
+  void MaxTimeLapsed(base::Time current_time);
+
+  Profile* profile_;
+
+  // Base key all prefs are stored under.
+  const std::string pref_key_;
+
+  // Base key used for histograms.
+  const std::string histogram_key_;
+
+  // Max number of sessions/days before the promo stops.
+  const int max_sessions_;
+  const int max_days_;
+
+  // Has Init been invoked?
+  bool did_init_;
+
+  // Return value from ShouldShow.
+  bool show_;
+
+  // Initial time the promo was first shown.
+  base::Time initial_show_;
+
+  DISALLOW_COPY_AND_ASSIGN(PromoCounter);
+};
+
+#endif  // CHROME_BROWSER_INSTANT_PROMO_COUNTER_H_