Add Incognito Navigation histograms

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 a17bd3d33d7a34a69f15a94de0452dca70a07f92..3397dd2f7e338067e9049d4c84a96bbb88417ebb 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -31558,8 +31558,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Navigation.MainFrameScheme" enum="NavigationScheme">
-  <owner>cbentzel@chromium.org</owner>
-  <owner>davidben@chromium.org</owner>
+  <owner>elawrence@chromium.org</owner>
+  <owner>estark@chromium.org</owner>
   <summary>The scheme of the URL for each main-frame navigation.</summary>
 </histogram>
 
@@ -31574,8 +31574,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="Navigation.MainFrameSchemeDifferentPage"
     enum="NavigationScheme">
-  <owner>cbentzel@chromium.org</owner>
-  <owner>davidben@chromium.org</owner>
+  <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
@@ -31583,6 +31583,25 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Navigation.MainFrameSchemeDifferentPageOTR"
+    enum="NavigationScheme">
+  <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.
+  </summary>
+</histogram>
+
+<histogram name="Navigation.MainFrameSchemeOTR" enum="NavigationScheme">
+  <owner>elawrence@chromium.org</owner>
+  <owner>estark@chromium.org</owner>
+  <summary>The scheme of the URL for each main-frame navigation while in
+    incognito.
+  </summary>
+</histogram>
+
 <histogram name="Navigation.OnBeforeUnloadOverheadTime" units="ms">
   <owner>carlosk@chromium.org</owner>
   <summary>