Histogram the scheme of an origin on the 1st navigation to it.

components/navigation_metrics/navigation_metrics.cc

Index: components/navigation_metrics/navigation_metrics.cc
diff --git a/components/navigation_metrics/navigation_metrics.cc b/components/navigation_metrics/navigation_metrics.cc
index e0d61c769f7b6a5daa6c876951b4870d02babf58..314ab74c81e2adae1ce5caa6006ffd0c0986fd9c 100644
--- a/components/navigation_metrics/navigation_metrics.cc
+++ b/components/navigation_metrics/navigation_metrics.cc
@@ -47,7 +47,10 @@ static_assert(arraysize(kSchemeNames) == SCHEME_MAX + 1,
 
 namespace navigation_metrics {
 
-void RecordMainFrameNavigation(const GURL& url, bool is_in_page) {
+void RecordMainFrameNavigation(const GURL& url,
+                               bool is_in_page,
+                               bool is_off_the_record,
+                               bool have_already_seen_origin) {
   Scheme scheme = SCHEME_UNKNOWN;
   for (int i = 1; i < SCHEME_MAX; ++i) {
     if (url.SchemeIs(kSchemeNames[i])) {
@@ -55,10 +58,22 @@ void RecordMainFrameNavigation(const GURL& url, bool is_in_page) {
       break;
     }
   }
-  UMA_HISTOGRAM_ENUMERATION("Navigation.MainFrameScheme", scheme, SCHEME_MAX);
-  if (!is_in_page) {
-    UMA_HISTOGRAM_ENUMERATION(
-        "Navigation.MainFrameSchemeDifferentPage", scheme, SCHEME_MAX);
+
+  if (is_off_the_record) {
+    if (!have_already_seen_origin) {
+      UMA_HISTOGRAM_ENUMERATION("Navigation.SchemePerUniqueOriginOTR", scheme,
+                                SCHEME_MAX);
+    }
+  } else {

[felt, 2016/04/07 02:28:04]

nit: could you simplify this by returning early?

[palmer, 2016/04/07 23:45:43]

Simplified in a different way.

+    if (!have_already_seen_origin) {
+      UMA_HISTOGRAM_ENUMERATION("Navigation.SchemePerUniqueOrigin", scheme,
+                                SCHEME_MAX);
+    }
+    UMA_HISTOGRAM_ENUMERATION("Navigation.MainFrameScheme", scheme, SCHEME_MAX);

[felt, 2016/04/07 02:28:04]

do we still want to calculate MFS like normal for OTR pages?

[palmer, 2016/04/07 23:45:43]

Oh, right. Yep!

+    if (!is_in_page) {
+      UMA_HISTOGRAM_ENUMERATION("Navigation.MainFrameSchemeDifferentPage",
+                                scheme, SCHEME_MAX);
+    }
   }
 }