MD Settings: Add feature flag for showing content settings in a per-origin view.

chrome/browser/flag_descriptions.cc

Index: chrome/browser/flag_descriptions.cc
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 71e11e2db6077b00ec0712d856766771b4595da7..71c0017a29c796237f7356b797369c4050784b2c 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -243,6 +243,12 @@ const char kTopChromeMdMaterial[] = "Normal";
 
 const char kTopChromeMdMaterialHybrid[] = "Touch";
 
+const char kSiteDetails[] = "Site Details";
+
+const char kSiteDetailsDescription[] =
+    "Adds UI in MD Settings to view all content settings for a specific "
+    "origin.";
+
 const char kSiteSettings[] = "Site settings with All sites and Site details";
 
 const char kSiteSettingsDescription[] =