Report frequency of single page app navigations to UMA

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

Index: third_party/WebKit/Source/core/loader/FrameLoaderTypes.h
diff --git a/third_party/WebKit/Source/core/loader/FrameLoaderTypes.h b/third_party/WebKit/Source/core/loader/FrameLoaderTypes.h
index 67fff48fa79c6489e3fb580cbc341aba6d09b798..b183492a056c70baa32b013ceee3ecc1ff115293 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoaderTypes.h
+++ b/third_party/WebKit/Source/core/loader/FrameLoaderTypes.h
@@ -94,6 +94,17 @@ enum class ProgressBarCompletion {
   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