Use is_same_document term instead of is_in_page for metrics.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 8b5dd5c804e344df612a0a8530a124c680d98038..300c9bceea69e3018c8d06eac4e00958724deefb 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -31956,9 +31956,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>elawrence@chromium.org</owner>
   <owner>estark@chromium.org</owner>
   <summary>
-    The scheme of the URL for each main-frame navigation that goes to a
-    different page. Transitions like fragment change or history.pushState are
-    excluded.
+    The scheme of the URL for each main-frame navigation that replaces a
+    document object. This is not reported for reference fragment navigations,
+    pushState/replaceState, same page history navigation.

[Ilya Sherman, 2017/05/09 03:46:56]

nit: s/same/or same (ditto below)

[Eugene But (OOO till 7-30), 2017/05/09 13:25:23]

Done.

   </summary>
 </histogram>
 
@@ -31967,9 +31967,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>elawrence@chromium.org</owner>
   <owner>estark@chromium.org</owner>
   <summary>
-    The scheme of the URL for each main-frame navigation that goes to a
-    different page while in incognito. Transitions like fragment change or
-    history.pushState are excluded.
+    The scheme of the URL for each main-frame navigation that replaces a
+    document object while in incognito. This is not reported for reference
+    fragment navigations, pushState/replaceState, same page history navigation.
   </summary>
 </histogram>