Report frequency of single page app navigations to UMA

third_party/WebKit/Source/core/loader/FrameLoaderTypes.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 76 matching lines @@
   kScrollRestorationManual
 };
 
 enum class ProgressBarCompletion {
   kLoadEvent,
   kResourcesBeforeDCL,
   kDOMContentLoaded,
   kResourcesBeforeDCLAndSameOriginIFrames
 };
 
+// This enum is used to index different kinds of single-page-application
+// navigations for UMA enum histogram. New enum values can be added, but
+// existing enums must never be renumbered or deleted and reused.
+// This enum should be consistent with SinglePageAppNavigationType in
+// tools/metrics/histograms/enums.xml.
+enum SinglePageAppNavigationType {
+  kSPANavTypeHistoryPushStateOrReplaceState = 0,
+  kSPANavTypeSameDocumentBackwardOrForward = 1,
+  kSPANavTypeOtherFragmentNavigation = 2,
+  kSPANavTypeCount
+};
 }  // namespace blink
 
 #endif