Workaround for a crashing appcache bug seen on the crash servers

webkit/appcache/appcache_histograms.h

 // Copyright (c) 2011 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 WEBKIT_APPCACHE_APPCACHE_HISTOGRAMS_H_
 #define WEBKIT_APPCACHE_APPCACHE_HISTOGRAMS_H_
 #pragma once
 
 #include "base/basictypes.h"
 
@@ skipping 16 matching lines @@
     READ_HEADERS_ERROR, READ_DATA_ERROR, UNEXPECTED_DATA_SIZE, CHECK_CANCELED,
     NUM_CHECK_RESPONSE_RESULT_TYPES
   };
   static void CountCheckResponseResult(CheckResponseResultType result);
 
   static void AddTaskQueueTimeSample(const base::TimeDelta& duration);
   static void AddTaskRunTimeSample(const base::TimeDelta& duration);
   static void AddCompletionQueueTimeSample(const base::TimeDelta& duration);
   static void AddCompletionRunTimeSample(const base::TimeDelta& duration);
 
+  static void AddMissingManifestEntrySample();
+
+  enum MissingManifestCallsiteType {
+    CALLSITE_0, CALLSITE_1, CALLSITE_2, CALLSITE_3,
+    NUM_MISSING_MANIFEST_CALLSITE_TYPES
+  };
+  static void AddMissingManifestDetectedAtCallsite(
+      MissingManifestCallsiteType type);
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AppCacheHistograms);
 };
 
 }  // namespace appcache
 
 #endif  // WEBKIT_APPCACHE_APPCACHE_HISTOGRAMS_H_