Add field trial and flag to mark HTTP as non-secure.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 524a8fca18d4e0d81f53602c43d8eb89f392b896..94e4e1a408406d88fbac8cce1acfe77c0ec559a1 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -801,6 +801,9 @@ const char kManualEnhancedBookmarks[] = "manual-enhanced-bookmarks";
 const char kManualEnhancedBookmarksOptout[] =
     "manual-enhanced-bookmarks-optout";
 
+// Use to opt-in to marking HTTP as non-secure.
+const char kMarkHttpAsNonSecure[]           = "mark-http-as-non-secure";
+
 // Forces the maximum disk space to be used by the media cache, in bytes.
 const char kMediaCacheSize[]                = "media-cache-size";