Add histograms and NetLog for host cache persistence

net/log/net_log_event_type_list.h

 // Copyright (c) 2012 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.
 
 // NOTE: No header guards are used, since this file is intended to be expanded
 // directly into net_log.h. DO NOT include this file anywhere else.
 
 // In the event of a failure, a many end events will have a |net_error|
 // parameter with the integer error code associated with the failure.  Most
 // of these parameters are not individually documented.
@@ skipping 3190 matching lines @@
 
 // This event is emitted when HttpServerPropertiesManager is persisting
 // in-memory version of HttpServerProperties to prefs/disk.
 // parameters:
 //  {
 //    "servers": <List of servers and their protocol usage information>,
 //    "supports_quic": <Local IP addresses that used QUIC>,
 //    "version": <The version number>,
 //  }
 EVENT_TYPE(HTTP_SERVER_PROPERTIES_UPDATE_PREFS)
+
+// -----------------------------------------------------------------------------
+// HostCachePersistenceManager related events
+// -----------------------------------------------------------------------------
+
+// The start/end of getting the persisted HostCache value and restoring it.
+// The END phase contains the following parameters:
+//  {
+//    "success": <Whether the persisted HostCache was restored successfully>,
+//  }
+EVENT_TYPE(HOST_CACHE_PREF_READ)
+
+// This event is created when the HostCachePersistenceManager writes the cache
+// contents to prefs.
+EVENT_TYPE(HOST_CACHE_PREF_WRITE)
+
+// This event is created when the HostCachePersistenceManager starts the timer
+// for writing a cache change to prefs.
+EVENT_TYPE(HOST_CACHE_PERSISTENCE_START_TIMER)