Remove ActivityLogState

All activity logging is done on the UI thread now, so there's no
need for a thread-safe cache of extension whitelists or ActivityLog
active state.

Bug: 268984
Change-Id: I3c35017cb8413be59a270a96e587f3c401e80b88
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1849419Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704850}

chrome/browser/extensions/activity_log/activity_log.h

@@ -19,8 +19,6 @@
 #include "base/threading/thread.h"
 #include "chrome/browser/extensions/activity_log/activity_actions.h"
 #include "chrome/browser/extensions/activity_log/activity_log_policy.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_registry_observer.h"
@@ -47,8 +45,7 @@ class ExtensionSystem;
 // each profile.
 //
 class ActivityLog : public BrowserContextKeyedAPI,
-                    public ExtensionRegistryObserver,
-                    public content::NotificationObserver {
+                    public ExtensionRegistryObserver {
  public:
   // Observers can listen for activity events. There is probably only one
   // observer: the activityLogPrivate API.
@@ -174,11 +171,6 @@ class ActivityLog : public BrowserContextKeyedAPI,
   // whether or not a consumer is active. Otherwise, checks active_consumers_.
   void CheckActive(bool use_cached);
 
-  // content::NotificationObserver:
-  void Observe(int type,
-               const content::NotificationSource& source,
-               const content::NotificationDetails& details) override;
-
   // Called once the ExtensionSystem is ready.
   void OnExtensionSystemReady();
 
@@ -240,8 +232,6 @@ class ActivityLog : public BrowserContextKeyedAPI,
   // reasons.
   bool is_active_;
 
-  content::NotificationRegistrar registrar_;
-
   base::WeakPtrFactory<ActivityLog> weak_factory_{this};
 
   FRIEND_TEST_ALL_PREFIXES(ActivityLogApiTest, TriggerEvent);