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

chrome/browser/profiles/profile_io_data.h

Index: chrome/browser/profiles/profile_io_data.h
diff --git a/chrome/browser/profiles/profile_io_data.h b/chrome/browser/profiles/profile_io_data.h
index 15166f29307b0a3896d8c16fcbc5b141ef853ea8..b56a6805df979b1c19058de3d5bf3a689dda8dc5 100644
--- a/chrome/browser/profiles/profile_io_data.h
+++ b/chrome/browser/profiles/profile_io_data.h
@@ -204,6 +204,12 @@ class ProfileIOData {
 
   bool IsOffTheRecord() const;
 
+  // In OffTheRecord profiles, we want to record a version of the
+  // Navigation.MainFrameScheme[DifferentPage] UMA histogram. The difference is
+  // that we only do it for the first time each origin is navigated to. For
+  // non-OTR profiles, this method is never called.
+  virtual bool HaveAlreadySeenOrigin(const url::Origin& origin);
+
   IntegerPrefMember* incognito_availibility() const {
     return &incognito_availibility_pref_;
   }