Adding cache hit/miss histograms to DiskBasedCertCache.

net/http/disk_based_cert_cache.h

 // Copyright (c) 2014 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 NET_HTTP_DISK_BASED_CERT_CACHE_H
 #define NET_HTTP_DISK_BASED_CERT_CACHE_H
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 29 matching lines @@
   // a reference to the certificate need to use X509Certificate::DupOSCertHandle
   // inside |cb|.
   void Get(const std::string& key, const GetCallback& cb);
 
   // Stores |cert_handle| in the cache. If |cert_handle| is successfully stored,
   // |cb| will be called with the key. If |cb| is called with an empty
   // string, then |cert_handle| was not stored.
   void Set(const X509Certificate::OSCertHandle cert_handle,
            const SetCallback& cb);
 
-  // Returns the number of in-memory MRU cache hits that have occured
+  // Returns the number of in-memory MRU cache hits that have occurred
   // on Set and Get operations. Intended for test purposes only.
   size_t mem_cache_hits_for_testing() const { return mem_cache_hits_; }
 
-  // Returns the number of in-memory MRU cache misses that have occured
+  // Returns the number of in-memory MRU cache misses that have occurred
   // on Set and Get operations. Intended for test purposes only.
   size_t mem_cache_misses_for_testing() const { return mem_cache_misses_; }
 
  private:
   class ReadWorker;
   class WriteWorker;
 
   // A functor used to free an OSCertHandle. Used by the MRUCertCache.
   struct CertFree {
     void operator()(X509Certificate::OSCertHandle cert_handle);
@@ skipping 27 matching lines @@
   int mem_cache_hits_;
   int mem_cache_misses_;
 
   base::WeakPtrFactory<DiskBasedCertCache> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(DiskBasedCertCache);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_DISK_BASED_CERT_CACHE_H