Implement permissions embargo for prompts which are repeatedly ignored.

chrome/common/chrome_features.cc

Index: chrome/common/chrome_features.cc
diff --git a/chrome/common/chrome_features.cc b/chrome/common/chrome_features.cc
index cb09f4cc2443f012208b0c327f55b88bf2849701..824bf87922e248fc727cc3af2d92a3f6dbd73aad 100644
--- a/chrome/common/chrome_features.cc
+++ b/chrome/common/chrome_features.cc
@@ -69,6 +69,11 @@ const base::Feature kBackspaceGoesBackFeature {
 const base::Feature kBlockPromptsIfDismissedOften{
     "BlockPromptsIfDismissedOften", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables or disables whether permission prompts are automatically blocked
+// after the user has ignored them too many times.
+const base::Feature kBlockPromptsIfIgnoredOften{
+    "BlockPromptsIfIgnoredOften", base::FEATURE_DISABLED_BY_DEFAULT};
+
 #if defined(OS_MACOSX)
 // Enables the new bookmark app system (e.g. Add To Applications on Mac).
 const base::Feature kBookmarkApps{"BookmarkAppsMac",