Add a histogram for tracking web store promo

chrome/common/extensions/extension_constants.h

 // 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_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 #pragma once
 
 #include "base/basictypes.h"
 
@@ skipping 221 matching lines @@
     0xf7, 0x0d, 0x01, 0x01, 0x05, 0x05, 0x00
   };
 
   // Don't remove items or change the order of this enum.  It's used in
   // histograms and preferences.
   enum LaunchContainer {
     LAUNCH_WINDOW,
     LAUNCH_PANEL,
     LAUNCH_TAB
   };
+
+  // The name of the apps promo histogram.
+  extern const char* kAppsPromoHistogram;
+
+  // The buckets used in the apps promo histogram.
+  enum AppsPromoBuckets {
+    PROMO_LAUNCH_APP,
+    PROMO_LAUNCH_WEB_STORE,
+    PROMO_CLOSE,
+    PROMO_EXPIRE,
+    PROMO_BUCKET_BOUNDARY = PROMO_EXPIRE + 1
+  };
 }  // extension_misc
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_