Split Blacklist from ExtensionSystem.

chrome/browser/extensions/blacklist.h

Index: chrome/browser/extensions/blacklist.h
diff --git a/chrome/browser/extensions/blacklist.h b/chrome/browser/extensions/blacklist.h
index 4b9d0bfdea6c44666ace81ca9429278e68b496f2..c4e438a5fe169ed90b1af708e13baa0e8aa16c36 100644
--- a/chrome/browser/extensions/blacklist.h
+++ b/chrome/browser/extensions/blacklist.h
@@ -16,10 +16,15 @@
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "chrome/browser/safe_browsing/database_manager.h"
+#include "components/keyed_service/core/keyed_service.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/blacklist_state.h"
 
+namespace content {
+class BrowserContext;
+}
+
 namespace extensions {
 
 class BlacklistStateFetcher;
@@ -27,7 +32,8 @@ class Extension;
 class ExtensionPrefs;
 
 // The blacklist of extensions backed by safe browsing.
-class Blacklist : public content::NotificationObserver,
+class Blacklist : public KeyedService,
+                  public content::NotificationObserver,
                   public base::SupportsWeakPtr<Blacklist> {
  public:
   class Observer {
@@ -71,6 +77,8 @@ class Blacklist : public content::NotificationObserver,
 
   ~Blacklist() override;
 
+  static Blacklist* Get(content::BrowserContext* context);
+
   // From the set of extension IDs passed in via |ids|, asynchronously checks
   // which are blacklisted and includes them in the resulting map passed
   // via |callback|, which will be sent on the caller's message loop. The values