Adding cache hit/miss histograms to DiskBasedCertCache.

net/http/disk_based_cert_cache.h

Index: net/http/disk_based_cert_cache.h
diff --git a/net/http/disk_based_cert_cache.h b/net/http/disk_based_cert_cache.h
index 5719cc649b5322f9284af753f29b70fe81adcbe4..36caaa130dfd1adf0e49308a0f21dea6c820678a 100644
--- a/net/http/disk_based_cert_cache.h
+++ b/net/http/disk_based_cert_cache.h
@@ -47,11 +47,11 @@ class NET_EXPORT_PRIVATE DiskBasedCertCache {
   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_; }