Move prefix_set and parts of safe_browsing_util into a new component safe_browsing_db.

chrome/browser/safe_browsing/safe_browsing_store.h

Index: chrome/browser/safe_browsing/safe_browsing_store.h
diff --git a/chrome/browser/safe_browsing/safe_browsing_store.h b/chrome/browser/safe_browsing/safe_browsing_store.h
index a12b9f3f2548c17b8ed7ee771ad2fee02bf94696..e4bd723528abd88db2a9b70b9841d72477ff9c20 100644
--- a/chrome/browser/safe_browsing/safe_browsing_store.h
+++ b/chrome/browser/safe_browsing/safe_browsing_store.h
@@ -13,9 +13,12 @@
 #include "base/callback_forward.h"
 #include "base/containers/hash_tables.h"
 #include "base/time/time.h"
-#include "chrome/browser/safe_browsing/prefix_set.h"
 #include "chrome/browser/safe_browsing/safe_browsing_util.h"
 
+namespace safe_browsing {
+class PrefixSetBuilder;
+};
+
 namespace base {
 class FilePath;
 }